indexOf() - FUNCTION

indexOf() Function

The indexOf() Function is used to find the starting position of the substring.

Example :

<html>
<body>  
<script>

	var x = "Hello Beautiful World"
	var y = x.indexOf("Beautiful")
	document.write("The substring is located at the position ",y)
    
</script>      
</body>
</html>

Output :

The substring is located at the position 6

In the above code, we have declared a String Hello Beautiful World and assigned it to a variable x.

var x = "Hello Beautiful World"

And we would be searching the substring Beautiful, from the String, Hello Beautiful World.

So, we have used the indexOf() Function to find the substring Beautiful.

var y = x.find("Beautiful")

And what indexOf() Function does is, goes to the String Hello Beautiful World and searches for the position of the substring Beautiful.

And finds the substring Beautiful in the 6th position. And the position (i.e. 6) is stored in variable y.

And thus prints the position.

document.write("The substring is located at the position ",y)

Output :

The substring is located at the position 6

Now, let us say you have the below String,

"The Beautiful world is Beautiful indeed"

And you have to search for the second occurrence of Beautiful.

To solve this, you can add a second and a third parameter used by indexOf() function that tells the range, and in between the range the substring can be checked.

Let us see with the below example.

Example :

<html>
<body>  
<script>

	var x = "The Beautiful world is Beautiful indeed"
	var y = x.indexOf("Beautiful", 20, 35)
	document.write("The substring is located at the position ",y)
    
</script>      
</body>
</html>

Output :

The substring is located at the position 23

So, if you see the above output, only the second occurrence of Beautiful is searched for.

That is because of the below line,

var y = x.indexOf("Beautiful", 20, 35)

Where we have specified the the range as 20 and 35, in second and third parameter.

Which says that search for the substring Beautiful in the positions between 20 to 35.

And thus we got the position as 23 assigned to the variable y,

❮❮ PREV NEXT ❯❯