JavaScript functions with returning variables

JavaScript functions are used to execute part of the code repeatedly. They are best used in different scripts to manage frequently used script parts. We will start with simple function syntax.

function name(){
//Code inside function
}

Let us start with an example.

<script language='JavaScript' type='text/JavaScript'>
function my_fun(){
document.write('Welcome to plus2net');
}
my_fun(); // Call to function
</script>

By adding function we can't use it. We need to call the function to execute the code kept inside the function. The line at the end of the above code call the function to execute it.

Passing a string variable to function.

We can supply a variable to the function and use the same to process inside it

<script language='JavaScript' type='text/JavaScript'>
function my_fun(str){
document.write('Welcome to ' + str);
}
my_fun('plus2net');
</script>

Getting return variable from function.

We can input two integers to function and get the sum of the two integers as return variable to calling script. We used parseInt function to convert input

<script language='JavaScript' type='text/JavaScript'>
function my_fun(v1,v2){
var v3= v1 + v2;
return v3;
}
var result=my_fun(5,8);
document.write('Sum of two number is ' + result);
</script>

Function Local and Global Variable

<script>
var v1=5 // Global variable 
function my_fun(){
var v1=2
document.write(v1)
}
my_fun()
</script>

Above code will print the value of v1 as 2 ( not 5 ) as v1 is local variable inside the function.

<script>
var v1=5 // Global variable 
function my_fun(){
document.write(v1)
}
my_fun()
</script>

Above code will print the value of v1 as 5 as we have declared v1 as global variable and using the same inside the function.

<script>
var v1=5 // Global variable 
function my_fun(){
var v1=2
document.write('Inside function v1 = ' + v1 + "<br>")
}
my_fun()
document.write('Outside function v1 = ' + v1 + "<br>")
</script>

Output

Inside function v1 = 2
Outside function v1 = 5

This is how the variables outside the function retain its values even though the value is changed inside the function.

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JavaScript Functions

Passing a string variable to function.

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