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New Post has been published on www.eduonix.com - Jquery Objects and Events

Jquery Objects and Events

Last time we tried some examples on events and event handlers. Today we will use jquery along with javascript code and perform some tasks using some inbuilt functions, events and effects. We are going to talk about jquery, how to implement it and how to manipulate certain elements in DOM.

All the inbuilt functions are written in the jquery.js file that is available on jquery.com website. We can directly download and use this file in our projects.

Process to download the file is as follows:

Open the browser and go to jquery.com website. Jquery.com homepage is shown below:

fig 1

Now click on Download jQuery button at your right side.

Now a page will open containing jQuery 1.x and jQuery 2.x headings.

fig 2

These are jquery versions. You can download any of the version.

We will download jQuery 1.x jQuery file.

You will get links for compressed version and uncompressed version, you can download any one. Difference in compressed and uncompressed version is that compressed version do not have explanation in comments and it is unreadable whereas uncompressed version has explanation and can be read.

We will download the compressed file, so click on Download the compressed, production jQuery 1.11.0.

The content of the file get’s displayed in the browser itself, it is difficult to understand.

Now create a folder on the desktop and name it as sec4_ch8.

Open a new notepad document and name it as jquery.js.

Now copy the whole content from the browser and paste it in the jquery.js file, save it and close the file.

Creating a HTML page:

Open a new notepad++ document and save it as index.html in the newly created folder, sec4_ch8.

Write the following html code and open the html file in the browser:

<!DOCTYPE html> <html> <head> <title>JQuery</title> </head> <body> </body> </html>

Output of the above code is shown below:

fig 3

Now we want to demonstrate various things using jquery in this tutorial, so let us include the file jquery.js in index.html document.

The file is always included in the head section of the html document.Code for including the file in html document is given below:

Now let’s try something practically.

Grabbing an object and applying style to it:

To have an object, first create a heading in the body section as shown below:

<h1>This is a heading</h1>

This h1 tag is our object now. To grab this object using jquery following code written in the body section below h1 tag is shown below:

Here, we wish to apply red color to the heading text. So we have grabbed the h1 object and added a class called red to it.

To grab an object from DOM we need to use jquery object i.e. $ followed by parenthesis. Whatever we want to grab is put in the parenthesis.

$ indicates jquery and $(‘h1’) grabs or selects all the h1 tags in the html document.

.addclass(‘red’) is the action taken on the h1 tag of adding a class named red to it.

This alone will not apply red color to the heading text. We have just finished assigning a class to h1 tag.

Now to apply red forecolor style we need to assign styling to the class red in the head section. The code is shown below:

<head> <title>JQuery</title> <style> .red color:red; </style> <script type="text/javascript" src="jquery.js"></script> </head>

The whole head section code is shown above.

We have applied the styling in the

tags.

Styling is done to the class red. Hence it is written as .red, because all classes are preceeded by a period in CSS.

Then inside the curly braces selector color is given red color value.

The output is shown below:

fig 4

In the above output we can see that the heading received red forecolor. In this case we have assigned the style through jquery.

We had added a class to h1 tag by selecting it through jquery, but if you see in the developers tool windows Element tab of browser, you will see that it has been directly added to h1 tag , it is shown below:

<h1 class=”red”>This is a heading</h1>

You can get the Developers tools by going to Tools –> Developers Tools.

Next task:

Now do one thing. Cut the code given below from the body section and paste it in the head section below the script tag where jquery.js file has been included:

You have to be sure that you paste the above code below the script tag that contains the jquery.js file as source.

Now reload and see the output. It is shown below:

fig 5

Here we see that the red color of the heading have been lost and there is no class attribute in the h1 tag as before in the deelopers tools code.

This is because, we tried to add a class red to h1 tag before the h1 tag was defined.

We are calling it before h1 tag have been loaded. This means, it gets executed beforehand and when h1 tag is loaded it will not execute and hence we get heading without red forecolor.

A solution for this is to execute all the scripts and styling only after the html document is ready. This is achieved by adding document ready handler to the code. Modify the jquery code in the script tag in head section as shown below:

The statement, $(document).ready will allow the script to run only when the html document has loaded completely.

The jquery code is in the function which is a parameter of ready. This indicates that the function will execute only when the html document is ready.

Now reload the browser and you will get the same output as before i.e. heading with red color as shown in fig 4.

Grabbing the object and changing its content:

We have a h1 tag with the text This is a heading in the body section.

We have styled it using jquery in the head section.

The code we have in the script tag is as follows:

Just modify it by adding the following statement below $(‘h1′).addClass(‘red’);

$('h1').html('This heading is from jquery.');

This statement changes the actual content of the DOM object.

Here, we have selected all the h1 tags using $(‘h1’).

.html is used to change the actual contents of the selected objects.

Here, when we reload the browser, we will get This heading is from jquery instead of This is a heading which is the actual text of h1 tag in the body section.

The output is shown below:

fig 6

Now write another h1 tag in the body section as shown below:

<h1>Here is another heading</h1>

Reload the browser and see the output, output shown will be as follows:

fig 7

Here, instead of Here is another heading text for second heading, it has printed This heading is from jquery.

You will get the same output no matter any number of h1 tags are added to the body.

This is because using jquery selector “$(h1)” we have selected or grabbed all the h1 tags in the html document.

If you want that the selector should grab only first heading, you will have to add a class to it as follows:

<h1 class="myclass">This is a heading</h1>

Now go to the jquery code and add this myclass to the selector as shown below:

Here, myclass is added to the statement of .html, because we want to change only the first heading.

If we add it to the selector of addClass(‘red’), then only first heading will be shown in red color.

But we want all the headings in red color so we did not add myclass to the selector of addClass(‘red’).

Now reload the browser page and see the output. It is shown below:

fig 8

Here, you can see that only first heading’s text has been changed and the second heading’s text is as it is.

Now let’s look at some jquery events.

Jquery Events:

To see various events in jquery, just open a new tab in your browser and type jquery events in the address bar.

You will get a hyperlink Events|jQuery API Documentation. Click on it.

A page with address http://api.jquery.com/category/events/ appears containing number of events.

If you click on any of the event, you will get its description along with some examples. Just go through these events.

So let’s try a click event in our tutorial.

Create a button with caption Change Text and a heading in the body section. The code is shown below:

<button>Change Text</button> <h2>This is the text to change.</h2>

Now to do some action when we click the button, we want to change the content of the above given heading.

This can be done at the click event.

So write the following jquery click event in the script tag in the head section.

$(document).ready(function() $('button').click(function() $('h2').html("Here is some new text."); ); );

Here, when html document is ready, the button object is selected or grabbed using $(‘button’)

.click() indicates the click event i.e. whatever function written in this click function as a parameter will get executed when click event of button Change Text occurs or the user clicks on Change Text button.

In the function for click event we have changed the content of h2 tag using .html().

The output before click event occurs is shown below:

fig 9

The text in the h2 tag is This is the text to change. When we click on Change Text button, this text is to be changed.

Output after occurance of the click event is shown below:

fig 10

Here, after observing fig 9 and fig 10, we come to know that the text changes from This is the text to change to Here is some new text. on clicking the button Change Text.

Now let us see some jquery effects.

Jquery Effects:

Along with the events you can also apply many different effects to show animated effect and lot more.

So open your browser and type jquery effects in the address bar.

Click on the hyperlink Effects|jQuery API Documentation. A page with address http://api.jquery.com/category/effects/ will appear.

Go through all the effects. Click on one and you will get its description and examples.

So let’s try some jquery effects in our project.

For demonstrating events we had changed the text of heading tag h2, now we will give it an effect of sliding up on the button click.

So modify the statement $(‘h2′).html(“Here is some new text.”); in the jquery code in head section to $(‘h2′).slideUp(200); the whole code will look like this:

$(document).ready(function() $('button').click(function() $('h2').slideUp(200); ); );

In the statement $(‘h2′).slideUp(200); above after selecting h2 tag slideUp(200) function will let the heading slide up as fast or slow as specified.

Syntax of slideUp() is slideUp(duration,complete); –> here duration indicate how fast or slow the object should slide and complete indicates the function to be executed after sliding up of the object, however it can be optional as in our case.

For duration we can use strings “fast” or “slow” or can also give duration in numbers, higher values of number indicate slower animations and lower values of number indicate faster animation.

If we don’t give any value, it will take 400 as its default value.

In our case when we click on the button Change Text, the heading This is the text to change will slide upwards and disappear.

The current status of our webpage is as shown in fig 9.

The output after sliding up of the heading is shown below:

fig 11

To make the heading again visible and appear to slide down we can replace slideUp() to slideDown().

Or to make it toggle up and down on button click we can directly use slideToggle() effect as shown below:

$(‘h2’).slideToggle(200);

If we wish to change the heading as the caption of the button specifies and then toggle up and down, we can achieve it using the code shown below:

$(document).ready(function() $('button').click(function() $('h2').html("Here is some new text.").slideToggle(200); ); );

The statement, $(‘h2′).html(“Here is some new text.”).slideToggle(200); will toggle the heading up and down by changing the its content.

The output after execution of this code is shown below:

fig 12

We got this output after clicking the button. The heading has changed and slides up and down on every click of the button.

Similarly we can try number of effects using jquery.

Thus we finished demonstrating jquery features with events and effects.

#Java Script #Java Script Tutorial #JavaScript #JavaScript Tutorial #jQuery #jquery effects #jquery events #jQuery objects and events #jquery tutorial #Web Development #web programming #WebDevelopment #Web Programming Tutorials

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New Post has been published on www.eduonix.com - JQuery Project

JQuery Project

In this tutorial we are going to create a JQyery Project. We will create a project that implements all or most of the knowledge that we have gained upto this point. It will include HTML, javascript, CSS, jquery, events and effects that we have gone through till now.

In this Jquery Project we are going to create a form to take input from a user and have some animation and validation also in it. View of the final form is shown below:

fig 1

So let’s start the process step by step.

Create a folder on the desktop and name it “sec4_ch9”.

Inside the folder “sec4_ch9”, create 2 folders named “CSS” and “js” respectively. CSS folder will be required to store .css file and js folder will be required to store javascript files.

Open a new notepad++ document and save it as “project.html” in the newly created folder “sec4_ch9”.

Write the following code in “project.html” document and save it.

<!DOCTYPE html> <html> <head> <title>Tabbed Form </title> </head> <body> </body> </html>

Output of the above code when the page is opened in the browser is shown below:

fig 2

Our sec4_ch9 folder has the following content:

fig 3

Create a file named jquery.js in the folder js which is inside sec4_ch9 folder on desktop.

Download jquery 1.x compressed version from jQuery.com by clicking on the hyperlink Download the compressed, production jQuery 1.11.0. as explained in the previous session.

Copy all the code that appears and paste it in the newly created jquery.js file in step 6. Save the file and close it.

We will be requiring this jquery.js file in our project so we need to link it with our project.html document. Follow the code written in head section to link the javascript file :

<head> <title>Tabbed Form </title> <script src="js/jquery.js" type="text/javascript"></script> </head>

Here, src attribute has the value “js/jquery.js”. This is the path of jquery.js file. jquery.js file is located in the js folder which is in turn located in the sec4_ch9 folder where project.html document is located.

Since project.html document and js folder are located in the same folder, the path till js folder is known to project.html. Hence path to jquery.js file is given only “js/jquery.js”.

Write the following code to create a form in project.html document body section.

<body> <form name="myform" onsubmit="return validateForm()"> <ul> <li class="title">Who Are You?</li> <li class="fields"> <label>*First Name : </label><br/> <input id="first_name" type="text" class="req"/><br/> <label>Middle Name : </label><br/> <input id="middle_name" type="text"/><br/> <label>Last Name : </label><br/> <input id="last_name" type="text"/><br/> <label>*Email : </label><br/> <input id="email" type="text" class="req"/><br/> </li> <li class="title">Where Are You?</li> <li class="fields"> <label>City : </label><br/> <input id="city" type="text"/><br/> <label>*State : </label><br/> <input id="state" type="text" class="req"/><br/> <label>Country : </label><br/> <input id="country" type="text"/><br/> </li> <li class="title">What Do You Do?</li> <li class="fields"> <label>*Occupation : </label><br/> <input id="occupation" type="text" class="req"/><br/> <label>Company : </label><br/> <input id="company" type="text"/><br/> <label>Company Location : </label><br/> <input id="location" type="text"/><br/> </li> </ul> </form> </body>

Explanation of the above code:

The form in the above code is given a name myform in the name attribute of the form tag and a function validateForm() is called on its onsubmit event.

The label and input elements are arranged in an un-ordered list.

Mandatory input field is shown by specifying an asterisk(*) on its label.

The li tags for all the headings in the form viz. Who Are You?, Where Are You? and What Do You Do? define a class called title that can be styled later in the .css file.

The li tags for the input fields define a class called fields for styling.

The mandatory input fields also define a class called req that will be used for validation later.

This was the designing part of the form. The output of the form is shown below:

fig 4

Thus we finished the designing part i.e. HTML part of JQuery Project

This form looks very ugly. It need to be styled to make it look attractive and comfortable for user to fill it.

Now open another new notepad++ document and save it as style.css in the folder CSS which is inside sec4_ch9 folder.

Write the following code in this style.css file and save it:

body width:500px; margin:auto; text-align:center; li list-style:none; li.fields margin:0; padding:1em 0; li.title cursor:pointer; font-weight:bold; font-size:1.5em; line-height:2em; background:#e3e3e3; border-bottom:1px solid #c5c5c5; border-top:1px solid white; .hide display:none;

Explanation of the above css code:

The above code is used to make the form presentation more attractive.

As we saw in fig 4, the form elements are aligned towards the left side of the browser.

So to align all the form elements at the center we use the following code snippet:

body width:500px; margin:auto; text-align:center;

Here, body with curly braces indicates that whatever styling done inside it will be applied to all the elements on the page.

So we have applied a width of 500 pixels and have aligned text at the center.

margin:auto; indicates that all the elements will take their place at the center no matter how small or big the browser window is.

Due to this body styling all the form elements will br arranged at the center along with the text.

Next styling is applied to the li tag as shown below:

li list-style:none;

Here, list-style:none; will remove all the bullets of un-ordered list.

Next we have a class fields defined in li tags. Its styling is shown below:

li.fields margin:0; padding:1em 0;

Here, the li with class fields is given no margin. But a padding of 1em is given at top and bottom of the li tag containing fields as its class and no padding is given to left and right.

Next we have the class title that is defined in the li tag of the 3 headings. Styling of title class is shown below:

li.title cursor:pointer; font-weight:bold; font-size:1.5em; line-height:2em; background:#e3e3e3; border-bottom:1px solid #c5c5c5; border-top:1px solid white;

The title class is styled with the following styles:

cursor:pointer; indicates that when the cursor is positioned on the li tag element having class title, it will turn to a hand pointer.

font-weight:bold; will make the text of the li tag content bold.

font-size:1.5em; will increase the size of the li tag content to 1.5em.

line-height:2em; will increase the padding block height to 2em.

background:#e3e3e3; will give a faint grey background color to the li tag containing title as its class.

border-bottom:1px solod #c5c5c5; This will give a solid bottom border of 1 pixel with a slight dark grey color than the previous.

border-top:1px solid white: will give a solid top border of 1 pixel with white color.

The next styling is for the class hide. It is shown below:

.hide display:none;

This is used in the animation part of the project. We will focus on it later.

The styling done in the style.css file will be applicable to the project.html document only after it is linked with it. So link the style.css document with the project.html document by adding the following link tag in the head section of project.html document:

Now reload the browser and see the output, the form will look as shown below:

fig 5

Thus we finished the styling part of JQuery Project

We now want to animate our form.

We want the tabs Where Are You? and What Do You Do? be closed initially and the fields of only Who Are You? tag should be shown.

For this we need to slide the heading tabs viz. Where Are You? and What Do You Do? downwards and their fields upwards. This is just to make it more comfortable to the user.

So now open a new notepad++ document and save it as animation.js in the js folder which is inside sec4_ch9 on the desktop.

Write the following code in it:

$(document).ready(function() $('li.fields').filter(':nth-child(n+4)').addClass('hide'); $('ul').on('click','li.title',function() $(this).next().slideDown(200).siblings('li.fields').slideUp(200); ); );

Explanation of the above css code:

We are using jquery for animating our form.

As we know, jquery code should execute only after the HTML document is ready we use the code shown below and write all the functions in this ready code block itself:

$(document).ready(function() // code here );

Here, $(document) is the selector that selects the HTML document and .ready(function() // code; ); starts executing jquery only when the selected html document is ready. The function () in ready function is its parameter.

Now our task is to initially hide the fields of tabs Where Are You? and What Do You Do? on page load. Hence the following statement:

$('li.fields').filter(':nth-child(n+4)').addClass('hide');

In this statement, we have first selected the list item that defines class fields using $(‘li.fields’) selector.This will select all the input fields on the form.

Now from the selected fields we have filtered the first 4 fields using .filter(‘:nth-child(n+4)’).

The purpose of .filter() in jquery is to reduce the set of matched elements to those that match the selector or pass the function’s test.

Value in the .filter() i.e. :nth-child(n+4) is a pseudo code used to select ‘n’ number of elements.

This nth-child pseudo code generally selects all elements that are the nth-child of their parent. Value of nth is “1 indexed” i.e. counting starts from 1.

So if you write :nth-child(n) , it will select all the elements.

But in our above code we have selected only first 4 fields and filtered it from the set of selected fields.

Next we have added a class called hide to the selected fields.

We had seen the styling of hide class in style.css file and had talked about discussing it later. This is the time for it.

Let us recall the styling for hide class:

.hide display:none;

Here, we have used a display selector with value none for the hide class.

So in animation.js file, as we have added this hide class to the selected fields, it will hide all these selected fields initially.

But we want the user to fill the form, so we will have to create a macanism to again make these fields visible.

This is done by the following code:

$('ul').on('click','li.title',function() $(this).next().slideDown(200).siblings('li.fields').slideUp(200); );

Here, we have selected the ul tag and used the .on action. Instead of using any perticular event directly we can use .on action and specify the event in it.

Task we want to perform is, when the user clicks on any of the tabs viz. Who Are You?, Where Are You? and What Do You do?, it should slide downwards and the fields that have been hidden previously should slide upwards.

Syntax for .on action is .on(‘an event’, ’the perticular element on which the event occurs’, a function performing task on occuring the event).

So in the above function we have provided click event, the li tag that defines the class title and the function containing code to achieve our objective.

The statement inside the function is given below:

$(this).next().slideDown(200).siblings('li.fields').slideUp(200);

In this, $(this) indicates the current element on which the click event have occurred. In simple words it represents the element on which we have clicked now.

The function next() indicates the next element i.e. the element below or next to the selected one.

slideDown(200) as we have seen in previous session is used to make an element to slide downwards.

siblings(‘li.fields’) selects the fields of the selected tab i.e. the tab on wich we have clicked.

slideUp(200) allows the selected fields to slide upwards.

In this way, when a user will click on any tab, the tab below it will appear to slide down and the the fields of selected tab will move upwards thus creating animation.

Now after completing the file animation.js we need to link it with project.html document. Write the following script tag in head section for this:

Now reload the browser and view the output as shown below:

fig 6

Thus we finished the animation part of JQuery Project.

Now its time for validation.

We will use javascript code for validation. So open a new notepad++ document and save it as validation.js in the js folder that is in sec4_ch9 folder on desktop.

Write the following code in this validation.js file:

function validateForm() for(var i=0;i<myform.elements.length;i++) if(myform.elements[i].className=="req" && myform.elements[i].value.length==0) alert('Please fill in all required fields'); return false; var email=document.getElementById('email').value; var atpos=email.indexOf('@'); var dotpos=email.lastIndexOf('.'); if(atpos<1

Explanation of the above css code:

In validation.js file we have written a function validateForm() that called on the submit event i.e. when we click on the submit button.

In this function, the code

for(var i=0;i<myform.elements.length;i++) if(myform.elements[i].className=="req" && myform.elements[i].value.length==0) alert('Please fill in all required fields'); return false;

Validates all the reqiured fields, those that have asterisk on their labels.

The for loop iterates from 0 to the count of the number of elements on the form which we get from myform.elements.length.

Next if statement checks a condition for each and every element as the loop iterates. The condition it checks is that if the element is given a class, then is that class “req” and if the class of element is “req”, then is that field empty.

If the above condition evaluates to true, then an alert message saying “Please fill in all required fields” is given.

The statement return false; replaces the evaluation output true with false. I mean when our condition evaluated to true an alert message is shown to us,because it returns true value. But if we return false,we replace our output of evaluation of if condition true with false. So it will not show us the alert message again and again, till the loop evaluates.

Next we have validated the email address field for valid email address with the following code:

var email=document.getElementById('email').value; var atpos=email.indexOf('@'); var dotpos=email.lastIndexOf('.'); if(atpos<1 || dotpos<atpos+2 || dotpos+2>=email.length) alert('Please type a valid email address'); return false;

Here, we have retrieved the value written by the user in the email field and stored it in the variable email using the statement

var email=document.getElementById('email').value;

Next we want to check the position of the “@” and period(.) in the email id to decide if it is valid or not.

So index of “@” and period is retrieved and stored in the variables atpos and dotpos respectively using the statements

var atpos=email.indexOf('@'); var dotpos=email.lastIndexOf('.');

We are using lastIndexOf(‘.’) to make sure that period(.) comes after the “@” in the email id.

After getting this we check if both @ and period(.) are at the wrong position in the email id with the if condition statement

if(atpos<1 || dotpos<atpos+2 || dotpos+2>=email.length)

If this condition evaluates to true, an alert message saying “Please type a valid email address” is shown.

return false is used to avoid continuous alert messages as explained above.

Thus we finished the validation part of JQuery Project

Output with validation is shown below:

Output when required fields are not filled:

fig 7

Output when required fields are filled but a valid email address is not given:

fig 8

Thus we finished developing our JQuery Project with the implementation of HTML, events, effects in jquery along with javascript.

#Java Script #Java Script Tutorial #JavaScript #JavaScript Tutorial #jQuery #JQuery Project #jquery tutorial #Web Development #web programming #WebDevelopment #Web Programming Tutorials

New Post has been published on www.eduonix.com - Javascript Events

Javascript Events

Today we will learn a new concept called events and event handlers. What is an event? An event is something that happens when an action is taking place in the browser. To deal with events we have handlers called as event handlers. These event handlers are nothing but attributes of the HTML tags, that help to perform a specified task when a particular event occurs.

Let us have a look on some of the events.

Event Description Abort Occurs when the user cancels loading of an image. Blur Occurs when input focus is removed from a form element (when the user clicks outside a field) or focus is removed from a window. Click Occurs when the user clicks on a link or form element. Change Occurs when the value of a form field is changed by the user. error Occurs when an error happens during loading of a document or image. focus Occurs when input focus is given to a form element or a window. Load Occurs when a page is loaded into Navigator. mouseout Occurs when the user moves the pointer off of a link or clickable area of an image map. mouseover Occurs when the user moves the pointer over a hypertext link. reset Occurs when the user clears a form using the Reset button. Select Occurs when the user selects a form element’s field. Submit Occurs when a form is submitted (i.e., when the user clicks on a submit button). unload Occurs when the user leaves a page.

Some of the event handlers are listed below:

onclick

onhover

onfocus

onload

onmouseover

ommouseout

onmousein

etc.

Let us now try it practically by using it in an html page. Follow the steps.

Create a new folder on desktop and name it as “sec3_ch7”.

Open a new notepad++ document and save it as “events.html” in the newly created folder.

Write the following code in “events.html” and save it.

<!DOCTYPE html> <html> <head> <title>Javascript Events</title> </head> <body> </body> </html>

Output of the above code is shown below:

fig 1

Let us try some of the examples of events. The task to be performed at any event is performed using functions.

Load event:

Load event occurs when a page or an image is loaded into the navigator.

So we will write a function giving an alert message that should execute as soon as the page is loaded. The code for function “sayHi()” written in the head section in the script tag is shown below:

As soon as this function executes, it shows an alert message greeting Hi.

But we want this function to execute at the page load event, so we need to call this function on the load event. The code written in body tag is shown below:

Here, onload is the attribute used in body tag to handle the load event.

Value of the onload attribute is sayHi(), return is to return the value.

Writing return is not compulsory, without it also you can get the output.

This means that the function sayHi() should be called when the page is loaded.

Output of the above code is shown below:

fig 2

Here we see that when page is loaded and an alert saying Hi appears on the page.

Click event:

Click event occurs when we click on a hyperlink or a form element.

Here, we will just create a button on the webpage. On the click event of this button we will call the above written sayHi() function.

Let us create a button having Click Me as its caption. The code written in the body section is given below:

<button onclick="return sayHi()">Click Me</button>

Here, we have created a button using

tags with a caption Click Me.

The function sayHi() should be called as soon as the user clicks the button. So onclick attribute is used in button tag to handle click event with sayHi() function as its value.

Due to this, as soon as the user clicks the “Click Me” button the function sayHi() gets called and an alert message of Hi appears on the webpage as seen on the onload event.

The output is shown below:

fig 3

We get the alert message Hi when we click on the button Click Me shown above.

Mouseover event:

Mouseover event occurs when the user moves the pointer over a hypertext link.

Let us have a heading in the body section and perform some task when the mouse pointer is on the heading.

The code below is written in the body section below the button:

<h1 id="heading" onmouseover="return changeMe()">This is a heading</h1>

In the above code, a heading This is a heading is created using h1 tag.

An id, “heading” is given to the h1 tag and onmouseover attribute is used to call the changeMe() function during the mouseover event.

The code for function changeMe() written in the script tag in the head section below sayHi() function is given below:

function changeMe() var heading=document.getElementById('heading'); heading.innerHTML="No Kidding";

The logic of the function says that when this function will be executed, the element having id as “heading” will be retrieved and stored in the variable heading. After this the text stored in the heading will be changed to No Kidding by the property innerHTML.

This function is called when we place the mouse pointer on the text in the h1 tag, since we know that the mouseover event is handled in the h1 tag calling changeMe() function.

Output before the mouse pointer is placed on the text This is a headingis shown below:

fig 4

Now when we place the mouse pointer on the text This is a heading, the changeMe() function will be called and will change the text to No Kidding. The output is shown below:

fig 5

Note one thing that as h1 tag is a block level element, it will change even if you move the pointer on the same horizontal line and not on the text specially. Block level element is that element that occupies whole width on the page and that always starts on a new line.

Mouseout event:

Mouseout event occurs when the user moves the pointer off of a link or clickable area of an image map.

In the above mouseover event we saw how the text This is a heading changed to No kidding.

Now in the mouseout event we will further change the text No Kidding again to This is a heading when the mouse moves away from the text.

For this we need to add the event handler attribute onmouseout to the h1 tag as shown below:

<h1 id="heading" onmouseover="return changeMe()" onmouseout="return changeMeBack()">This is a heading</h1>

Value of onmouseout attribute is changeMeBack() function that performs the task of changing the text No Kidding to This is a heading.

Logic of changeMeBack() function written in the script tag in head section below, changeMe function is shown below:

function changeMeBack() var heading=document.getElementById('heading'); heading.innerHTML="This is a heading";

The logic of changeMeBack() function has task opposite to changeMe() function.

It gets the element having id as heading in the variable heading and changes it to text This is a heading.

The page after execution of changeMe() function and before execution of changeMeBack() function is shown below:

fig 6

Now the output after execution of changeMeBack() function is shown below:

fig 7

Thus when mouse is over the text This is a heading, it changes to No Kidding and when mouse moves away from it or goes out, the text No Kidding changes to This is a heading again.

Now let’s try some events on form elements.

Create a simple form. The code written in the body section is shown below:

Form tag is used to create a form in HTML.

We have created a textfield to take name as input and a submit button.

The is used for the non breakable space, to shift the submit button below the textfield.

The output of the form is shown below:

fig 8

We will use focusin event and blurout event for the textfield one by one.

Focus event:

Focus event occurs when input focus is given to a form element or a window.

In this case, we will experience this event when we set the focus on the textfield.

When focus is set on the textfield, an alert should come saying “I am in the field”. This is done by writing a userdefined function called focusIn().

The function written in script tag in the head section is shown below:

function focusIn() alert("I am in the field");

When this function executes, it will show an alert saying I am in the field.

This function should be called on the focus event of the textfield.

The onfocus attribute is added to the input tag of textfield as shown below to achieve this:

Name : <input onfocus="return focusIn()" type="text" name="name"/>

Here, we have called the function focusIn() during the focus event of the textfield.

So now when we place the cursor in the textfield or click on the textfield or set focus on the textfield, an alert message will appear saying I am in the field.

The output is shown below:

fig 9

Next we will see the blur event.

Blur event:

Blur event occurs when input focus is removed from a form element (when the user clicks outside a field) or focus is removed from a window.

In this case, we will experience this event when we remove focus from the textfield.

When focus is removed from the textfield, an alert should come saying “I am out of the field”. This is done by writing a userdefined function called blurOut().

The function written in script tag in the head section is shown below:

function blurOut() alert("I am out of the field");

When this function executes, it will show an alert saying I am out of the field.

This function should be called on the blur event of the textfield.

The onblur attribute is added to the input tag of textfield as shown below to achieve this:

Name : <input onfocus="return focusIn()" onblur="return blurOut()" type="text" name="name"/>

Here, we have called the function blurOut() during the blur event of the textfield.

So now when we remove focus from the textfield i.e when we click somewhere outside the textfield, an alert message will appear saying I am out of the field.

The output is shown below:

fig 10

So here, when we click out of the textfield, we get the alert message I am out of the field.

Here, when focus is set in the textfield an alert message I am in the field appears and when the focus is removed, blur event occurs and an alert message I am out of the field appears.

Thus we finished demonstrating some of the events in javascript.

#Java Script #Java Script Tutorial #JavaScript #Javascript events and event handlers #JavaScript Tutorial #Web Development #web programming #WebDevelopment #Web Programming Tutorials

New Post has been published on www.eduonix.com - Javascript Loops

Javascript Loops

Today we are going to learn loops in javascript. Loops are mostly used to repeat the execution of certain statements. If you want to execute the same statement again and again number of times, instead of writing it number of times you can place it once in any of the loop iterating that many times. In this tutorial we will learn for loop, while loop and for/in loop. Let’s learn by creating a simple webpage. Follow the steps.

Create a folder named “sec2_ch2” on desktop.

Now open a new notepad++ document and save it as “loops.html” inside the folder “sec2_ch2” just created.

Write the following html code in it and open this “loops.html” page in a browser.

<!DOCTYPE html> <html> <head> <title>Javascript Loops</title> </head> <body> </body> </html>

Output of this code in shown below:

fig 1

Now we will start our javascript loops.

We know that javascript is to be written in

tags and script tag can be written in head as well as body section of the webpage.

So in this tutorial we will write all the code in body section.

So let’s start with for loop. Write the following code in body section.

The above code shows us the use of for loop.

Syntax of for loop encloses variable initialisation, condition checking and increment/decrement in a single line separated with semicolon.

The statements to be repeated are placed inside the curly braces.

Let’s understand how for loop executes.

In the for statement, the variable i is initialised to zero for the first time. This initialisation is done only once.

Next, the condition is checked. If it evaluates to true, the statement/statements in the curly braces are executed.

After execution of the statements, the control goes to the increment/decrement statement and the value of the variable is incremented/decremented as specified in the loop.

Then once again the condition is checked and statements are executed.

The steps iii and iv are repeated till the condition evaluates to true. The loop will terminate once the condition has evaluated to true.

In the code above, the statement document.write(“Number ” + i + “ “); will print the text given in it.

In this statement concatenation operator (plus sign) is used to concatenate the text Number and the value of i variable.

Brake tag is used to start every statement on a new line.

document.write(“for loop output

“);

statement is for our information.

Repeatition of the loop number of times is called iterations.

The output of above code is shown below:

fig 2

This output shows numbers only till 9 because once i increments to 10, the condition becomes false and hence the loop terminates, it cannot enter the curly braces to execute the statement.

To make the loop print numbers till 10, we need to change the condition from i<10 to i<=10. So that the condition remains true when i reaches 10.

The output of above code with condition i<=10 is shown below:

fig 3

Now let’s see while loop. Write the following code below the for loop inside

tags.

document.write("<br><b><i>while loop output</i></b><br>"); var j=0; while(j<5) document.write('Number ' + j + '<br>');

The above code shows us the use of while loop.

In the syntax of while loop, initialisation is done first, before the loop starts. Then the while statement contains the condition and then the body of loop contains other statements that are to be executed along with the increment/decrement statement.

Let’s understand the execution of while loop.

In the above code, first variable j is initialised to zero. This statement also is executed for the first time. i.e. only once.

Next control goes to while statement and checks the condition. If the condition evaluates to true, the statements in the curly braces are executed and the variable is also incremented/decremented as stated in the code.

Step ii above is repeated till the condition is true. Once the condition becomes false, the loop is terminated.

document.write(“ while loop output “); statement is given for our information.

The statement document.write(‘Number ‘ + j + ‘ ‘); is used for printing the statement. It is same as explained in for loop.

The output of while loop output is shown below:

fig 4

while loop output shows numbers from 0 to 4. If you change the condition from j<5 to j<=5, it will show numbers from 0 to 5.

Next is for/in loop.

For/in loop is used only with collections.

It’s syntax is not similar to the regular for loop.

Let’s see it practically.

As for/in loop works for collections, let’s declare an array and then use for/in loop to display all the elements of array. Write the following code below while loop in

tags.

document.write("<br><b><i>for/in loop output</i></b><br><br>"); var people=["Sally","Bob","Steve","Jen"]; for(x in people) document.write(people[x] + "<br>");

The above code shows us the use of for/in loop.

document.write(“ for/in loop output

“);

statement is for our information.

We have declared an array named people that contains some names.

We want to display all the values in the array people.

If it had not been for loops we would had displayed every value in the array as shown below:

document.write(people[0] + “<br>”); document.write(people[1] + “<br>”); document.write(people[2] + “<br>”); document.write(people[3] + “<br>”);

But we can display all the values with loops with minimum code.

The code for displaying the array values using for/in loop is:

for(x in people) document.write(people[x] + "<br>");

Syntax for for/in loop does not need initialisation, condition and increment/decrement as in for loop.

As for/in loop can traverse only through collections, its for statement contains a variable that can get each and every value in the collection.

In the above shown loop, x is the variable used for traversal, in is the keyword indicating from where should x take the value and people is the actual collection (array) that contains the values to be displayed.

Let’s understand the execution of for/in loop.

All collections start from zero(0) index, hence the variable x is by default initialised to zero(0). You can have any variable name.

When the loop starts executing, the variable , in this case, x gets the value at zeroth index from people array.

Now the value at index 0 in people array is displayed using the statement document.write(people[x] + “ “);

After executing the statements in curly braces, the variable x is auto-incremented. i.e. now x will become 1.

Now the value at index 1 will be displayed.

The statements iv and v will repeat until and unless all the array elements are not traversed.

The output of for/in loop is shown below:

fig 5

Displaying array elements using for loop.

We can display array elements using for loop as shown below:

document.write("<br><b><i>displaying array elements using for loop</i></b><br><br>"); for(k=0;k<people.length;k++) document.write(people[k] + "<br>");

Here, in for loop, k is the variable used for traversal.

The condition used is

k<people.length;

The condition indicates that k is less than the length of the array people.

We know , in javascript, array is an object and objects have properties.

length is also a property of some objects like arrays and strings.

length when used with a string tells us the number of characters in that perticular string and when used with array tells us the number of values in that perticular array.

If you add or delete some values from an array, the length will change accordingly.

The statement document.write(people[k] + “ “); will print the value at respective index k from array people.

Output of displaying array elements using for loop is shown below:

fig 6

Now, just add one more name to the existing people array manually as shown below:

var people=["Sally","Bob","Steve","Jen","Tom"];

We have added a new name Tom to the array. Now reload the page, you will find that the name Tom has also appeared in the list of names.

This is because, length property of array counts all the values in the array.

The output is shown below:

fig 7

Displaying array elements using while loop:

We can display array elements using for loop as shown below:

document.write("<br><b><i>displaying array elements using while loop</i></b><br><br>"); p=0; while(p<people.length) document.write(people[p] + "<br>"); p++;

Here, p is the variable initially intialised to zero(0). While declaring a variable var keyword is optional.

The condition in the while statement,

p<people.length

will traverse the whole array till the last element due to the length property as explained above.

The statement document.write(people[p] + “ “); will print the element at perticular index in the array people.

The variable p will be incremented by 1 with every iteration.

Thus it will continue till the length of the array i.e. 5. But we have 5 elements in the array just now, because we had added a new name Tom in it previously. And our condition is

p<people.length

that means p<5. Now if we have 5 elements and our condition is p<5, then how all the elements will be displayed?

This is because, in any array, elements are placed from index 0 and all the five elements will be completely filled in the array upto the index 4.

Now our condition is

p<people.length

, it means p<5. All the array elements will be traversed and displayed upto the index 4 and when p reaches 5, the condition will become false and the loop will be terminated.

In this way all the elements are displayed in the array.

The array elements displayed using while loop is shown below:

fig 8

Now, if you again remove one of the element from the existing array of people, only that many elements will be displayed using any of the above loops. Try it and view the output yourself.

Thus we finished the demontration of loops in javascript.

#Java Script #Java Script Tutorial #JavaScript #Javascript Loops #JavaScript Tutorial #Web Development #web programming #WebDevelopment #Web Programming Tutorials

New Post has been published on www.eduonix.com - Javascript Variables and Arrays

Javascript Variables and Arrays

Today we will learn how to declare and use javascript variables and arrays. We will create a simple html page and then learn different relating concepts along with declaration of varaiables and arrays in it and view the output on the webpage. Let’s start with variables first. Follow the step by step procedure to learn

Create a new folder on desktop with name “sec2_ch1”.

Now open a new notepad++ document and save it as “var_array.html” in the folder “sec2_ch1” created just now. Select “Save as type” as “Hyper Text Markup Language file (*.html*.htm*.shtm)”.

Write the following code in this “var_array.html” file and save it.

<!DOCTYPE html> <html> <head> <title>Variable & Arrays</title> </head> <body> </body> </html>

When we open this page in browser it will look as shown below:

fig 1

The title given in

tags in head section is shown on the title bar of the browser.

Now let’s turn to variables.

Variable is nothing but a location engaged to store a value.

This location is given a name for identification, which is called a variable name.

Giving a variable name to any location follows certain rules such as,

Variable names must begin with a letter.

Variable names can also begin with dollar symbol($) or an underscore(_).

Variable name is case sensitive. For example: age and Age are two different variables.

Creating a variable in javascript is most often referred to as “declaring” a variable.

So now, let’s declare variables.

We know that when we use any scripting language in .html file, we enclose the code other than html in

tags.

So to declare 2 variable in the head section of html file write the following code below the

tags.

Here in the above code we have declared a variable. var is a keyword used to declare a variable. car is the variable name and Honda is the value assigned to car variable.

Honda is a string and can be enclosed either in double quotes or single quotes.

In javascript you can declare a variable without var keyword also.

Just have a look on the code below:

Declaring a variable without var keyword is also right and will work.

Now, if you want to print something on the webpage, it should be done in the body section.

In javascript, a command document.write(); is used to print anything.

So write the following code in body section of the webpage.

The document.write(); command will print the text “Hello World!” on the webpage as it is as shown below.

fig 2

Now if we want to print the value stored in the variable car declared above, we should write it as follows:

document.write(car);

This statement will print the value stored in the variable car as shown below:

fig 3

Now if you change the value of car from Honda to Toyota, the statement document.write(); will also print Toyota on the webpage instead of Honda.

Let’s give integer values to variables.

We know that variables can store different types of values in it. So let’s declare 2 variables containing 2 integer values in head section.

var x=5; var y=10;

The variables x and y contains 5 and 10 values respectively.

If we want to print its addition, write the following statement in body section.

document.write(x+y);

You will see that addition of 5 and 10 is printed on the webpage as shown below:

fig 4

Integer values treated as strings:

We have seen the declaration of x and y variables above. The values are 5 and 10 are written without any quotes.

But if we write these integer values in quotes, they will be treated as strings.

Let’s see the demonstration below.

Declare 2 different variables in head section.

var x1='5'; var y1='10';

Here, the values 5 and 10 of variables x1 and y1 are enclosed in single quotes.

Now write the following statement in body section:

document.write(x1+y1);

You will get the following output:

fig 5

The output shown in the above figure is 510.

The statement document.write(x1+y1); has just concatenated or joined the two numbers.

This is due to enclosing the values 5 and 10 into single quotes. As soon as you enclose numbers in quotes, they no more remain numbers, they transform into strings.

So instead of adding them and giving answer as 15, the value of variable y1 is concatenated to the value of variable x1 giving answer as 510.

Concatenating string with variables:

Just see the following statement:

document.write("I have 5 apples.");

If we write the above statement in the body section, it will print as it is on the webpage.

But I want to print the value stored in the variable x declared somewhere above. To obtain this let’s write the following statement.

document.write("I have x apples.");

Here, instead of 5 we have used the variable x.

Now, let’s see its output:

fig 6

Here, according to the above code, we wished that the x will be replaced with x’s value after execution, but it has been printed as it is.

To obtain it we need to use concatenation operator. Plus sign (+) is called as the concatenation operator. It heps us to concatenate or join strings, variables, strings and variables, etc.

So to obtain our desired output just use concatenation operator in the above statement as follows:

document.write("I have " + x + " apples.");

Output is shown as follows:

fig 7

This same concept of concatenation is used to start printing each and every statement on new line in this tutorial.

After every printed statement a line brake is applied, so that new statement is printed on new line. An example of this is shown below:

document.write(x+y +"<br>"); document.write("I have x apples.<br>");

Here, in the first statement, (x+y) is an expression and to obtain its answer, it is written without quotes, but brake tag should be written in string format because it has to take the cursor to new line. So the expression and the string containing brake tag are concatenated.

In the next statement, we are printing a string itself, so brake tag need not require to be placed in separate quotes hence no concatenation here.

Some important things about variables:

Multiple variables can be created within one statement separating them with comma.

Eg: var lastname=”Deo”, age=30, job=”carpenter”;

We can span our declaration on multiple lines also.

Eg: var lastname=”Deo”, age=30, job=”carpenter”;

If you have declared a variable with a value and later you again declare the same variable. It will retain the value assigned to the variable declared firsr time.

For example, if you have declared a variable carname with value “Ford” as :

var carname=”Ford”;

And now you again declare the same variable without any value as:

var carname;

This carname variable will retain the value “Ford” assigned during its first time declaration. It will not give any error.

This was all about variables. Now let’s understand arrays.

Learining about arrays.

Array is a data structure which can store multiple values under a single variable.

If you want 3 values in your program, it is easy to declare 3 variables.

But if you need directly 100 values, it is a stupidity to declare 100 variables, at this situation you can use array.

Arrays are declared in 3 ways:

First way:

var cars = new Array();

Here we have created an array object called cars. This is a regular way of creating arrays. It creates an empty array.

Array has index to traverse through it. Array index always start from zero (0) onwards.

So to store values in above array, we can use the following statements:

cars[0]="Ford"; cars[1]="Toyota"; cars[2]="BMW";

According to the above statements, Ford will be stored at index 0 of cars array, Toyota will be stored at index 1 of cars array and BMW will be stored at index 2 of cars array.

Second way:

var cars = new Array(“Ford”, ”Toyota”, ”BMW”);

Here we have created an array object called cars and have directly assigned values to it . This is a condensed way of creating arrays.

According to the above statements, Ford will be stored at index 0 of cars array, Toyota will be stored at index 1 of cars array and BMW will be stored at index 2 of cars array.

Third way:

var cars =[“Ford”, ”Toyota”, ”BMW”];

Here we have directly assigned values to cars. This is a literal way of creating arrays.

According to the above statements, Ford will be stored at index 0 of cars array, Toyota will be stored at index 1 of cars array and BMW will be stored at index 2 of cars array.

Printing array values.

To print any value in array you can use the following statement.

document.write(cars[0] +”<br>”); document.write(cars[1] +”<br>”); document.write(cars[2] +" ... before changing<br>");

This will print the zero’th index value in cars array. i.e “Ford”, array value at index 1 i.e. “Toyota” and array value at index 2 i.e. “BMW”.

We can change a value in array at any index by just assigning a new value to that index as shown below:

cars[2]=”Dodge”;

Here, we have changed the value at index 2 from BMW to Dodge.

When you print it, it will show us Dodge.

document.write(cars[2] +" ... after changing<br>");

The output is shown below:

fig 8

Since arrays are objects they can have methods and properties as well.

Some properties are demonstrated below:

document.write("number of elements in cars array = " + cars.length + "<br>"); document.write("index of \"Toyota\" in cars array = " + cars.indexOf("Toyota"));

In the above statements, length and indexOf properties are used to count the number of array elements and to know the index of a particular array element respectively.

The output is shown below:

fig 9

In javascript, you are allowed to store different type of elements in single array.

Here, we finished with our variables and arrays. We will study traversal of arrays using loops in next section.

#Java Script #Java Script Tutorial #JavaScript #JavaScript Tutorial #Javascript Variables and Arrays #Web Development #web programming #WebDevelopment #Web Programming Tutorials

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New Post has been published on www.eduonix.com - Javascript Fundamentals

Javascript Fundamentals

Today we are going to start an introduction to Javascript and JQuery. It is used to do some processing in a webpage. In this tutorial we will learn Javascript fundaments that will be explained in detail in further tutorials. Let’s start with an introduction to Javascript.

What is Javascript?

Javascript was originally created by Netscape and was called ECMAscript.

Javascript is the main scripting language of the Web and can be executed by all types of web browsers.

Javascript runs on the client as opposed to the server.

Javascript is different from Java. It has nothing to do with Java programming language.

Uses of Javascript?

Javascript is used for the following things :

HTML Form Validation – to validate input elements for email, phone number etc.

Event Handling – to perform some action on an element we can use javascript libraries such as JQuery that contain various functions and events such as click, hover etc.

Javascript powers HTML5 features.

Using javascript we can also provide searching and autocomplete feature on the webpage.

Animations.

JQuery, Ajax and other libraries are all written in javascript.

Adding Javascript to an HTML page:

We can add a javascript code to an HTML page using

tags.

These

tags can be placed in head section as well as in body section.

We can add the javascript code to HTML page in two ways:

Write the javascript code directly in the script tags in HTML page

We can attach a separately written javascript (.js) file to the HTML page.

Let’s see an example.

<!DOCTYPE html> <html> <head> <script> inline Javascript goes here </script> <script type="text/javascript" src="myscript.js"></script> </head> <body> </body> </html>

Here, the statement “inline Javascript goes here” inside the tags indicates the actual code written in javascript. It is called inline here, because the code will be written within HTML page.

The next statement,

indicates that the externally written javascript file named “myscript.js” is attached to the HTML page to perform various actions.

Javascript Variables:

Variables in any language are the placeholders that can store different datatype values in it.

There are rules to define a variable.

Variables should start with a letter.

Variables are case sensitive

Declaration of an empty variable x is shown below:

var x;

Here var is a keyword used to declare a variable.

Declaration of variables with assignment of a value is shown below:

y=4; var y=4;

Here, two variable declaration statements are shown above.

The two statements are one and the same, i.e. they will do exactly the same work of declaring a variable y with value 4 assigned to it.

From this you might have understood that var keyword is not compulsory. We can declare variable without var keyword also.

Javascript Arrays:

Array is just a variable that holds more than one values.

Variables have a property to hold a single value. But if you want to store more values under a single variable, you can definitely use arrays.

Declaration of arrays is shown below:

var cars=new Arrays(); // this is an empty array having no values stored in it.

If you want to store values in this array, you can store it as follows:

cars[0]=”Honda”; cars[1]=”Toyota”; cars[2]=”Ford”;

Array index starts from zero(0).

You can assign values as shown above at every index.

Next way of declaring array along with the assignment of values is shown below:

var cars=new Array(“Honda”,”Toyota”,”Ford”);

This creates an array of cars with values assigned to it as parameters.

Javascript Loops:

Loops are used to run the same code over and over until a certain condition is met.

The loops in javascript are shown below:

For Loop: It loops through a block of code a number of times. You usually know the number of times.

While Loop: It loops through a block of code until a condition is true. You usually don’t know the number of times.

For In Loop: It loops through array object values.

Do—While Loop: It is same as While loop, only it checks the condition at the last. It is not used frequently.

Javascript Loop Syntax:

Here, we will see syntaxes of for loop and while loop to get an idea of the loops.

For Loop:

for(var i=0;i<5;i++) document.write(“number”+i+”<br/>”);

In for loop, the initialization, condition check and increment/decrement is done in a single statement.

document.write(); is a command that is used to print the output on the screen.

The loop will repeat 5 times, since the condition will remain true until i=4.

While Loop:

var i=0; while(i<5) document.write(“number”+i+”<br/>”); i++;

For while loop, we need to first initiate the variable before starting the loop.

Then the condition is checked, if condition is true the given statements in the curly braces are executed.

The output of both the above loops will be: number0 number1 number2 number3 number4

Javascript Functions:

A function is a block of code that runs when it is called.

It is mostly used to reduce the length and complexity of the program.

If a program requires same code to be written in most of the places, we can write function for it once and call it wherever required, thus reducing the programmer’s work.

Syntax for creating a function:

function someFunction() document.write(“This is some function”);

The function is defined with a keyword function followed by a function name and paranthesis.

Whatever statements present inside the opening and closing curly braces form the body of the function.

The function is not executed unless it is called.

Syntax for calling a function:

someFunction();

Calling a function is very simple. Just write the function name with paranthesis.

A function can have parameters also.

Javascript Objects:

Everything in javascript is an object.

Some built in objects are: String, Date, Array, Function, etc.

Objects have properties or characteristics.

In javascript properties can be accessed as follows:

objectName.propertyName

An example is shown below:

var greeting=”Hello”; var x=greeting.length;

Here, x is equal to 5 as it is equal to the length property of the “greeting” variable.

Thus we finished with an overview of Javascript Fundamentals. We will study each topic in detail in further tutorials.

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