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Learn more about JavaScript Function

Function is a group of JavaScript statements that we declare once in our script and call over and over again.

Features of JavaScript Function

JavaScript is created by function keyword, followed by function name and followed by parentheses ().

Function names can contain only letters, digits, underscores, and dollar signs.

Parentheses contain parameter names separated by commas – (parameter1, parameter2, parameter3, ….)

Within curly brackets write code to execute function.

Declaring a Function

function name( parameter1, parameter2, parameter3, parameter4, ….  )     statements     return value

Example:-

function calculateResult ( maths, english, science)     var totalMarks = maths + english + science;     return totalMarks;    alert ( “Total Marks are:” + calculateResult(70, 80, 90) );

Calling a function

After declare a function, we call a function by specifying the name of function, followed by an open parenthesis, comma-delimited parameters, and a closing parenthesis.

Example:-

alert ( “Total Marks are:” + calculateResult(70, 80, 90) );

Function Return

When JavaScript reaches a return statement, the function will stop executing. We use return statement to return a value from a function.

Syntax for the return keyword

return expression

Example-

function calculateResult ( maths, english, science)     var totalMarks = maths + english + science;     return totalMarks; // Now the function is defined, so it can be called

        document.write( “Total Marks are:” + calculateResult(70, 80, 90) );