Functions in javaScript

Function is a Self-contained block of statement.

Functions are used to divide a large code into module so that it is easy to debug the program.

 

Advantages:
Code Reusability.

Less Code: Less code is required in  javaScript because you don’t need to write the code again and again. It saves code

 

User defined Functions

The function which is defined by user is called User defined function.

 

Function definition

 

function  function_name(parameters)

{  

//function body

}  

Function Call

function_name();

 

Example 1( Using No parameter)

<script>

function show()

{ 

alert("hello welcome to  learningpoint92"); 

} 

</script> 

<input type="button" onclick="show()" value="getOutput "/>

Output:

Welcome To LearningPoint92

 

 

OR

<script> 

function show()  //function definition

{ 

document.write("hello welcome to  learningpoint92"); 

} 

show();  //function call

</script>

 

Output:

hello welcome to  learningpoint92

 

Example 2(Using parameter)

<script> 

function add(num1,num2){ 

alert("sum is:"+(num1+num2)); 

} 

</script> 

<input type="button" value="click" onclick="add(12,18)"/> 

 

Output:

Sum is:30

 

Example 3(Return Statement)

<script> 

function show(){ 

return "Hello surya";

}

 document.write(show()); 

</script> 

Output:

Hello surya

 

Example 4(Taking value from user)

<script> 

function add()  // defining function

{

var x =parseInt(prompt("Enter first number"));

var y =parseInt(prompt("Enter second number"));

alert("Sum is:"+(x+y));

}

add(); //function call

</script> 

Output:

Enter first number

23

Enter second number

20

Sum:43