JavaScript String indexOf() Method

JavaScript string indexOf() Method with example, by string literal, by string object (using new keyword), javascript string methods, charAt(index) method, concat(str) method, indexOf(str) method, lastIndexOf(str) method, lowerCase() method, upperCase() method, slice(beginIndex, endIndex) method, trim() method, toLowerCase(), slice(), concat(), charCodeAt() method etc.

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JavaScript String indexOf() method

The JavaScript string indexOf() method is used to search the position of a particular character or string in a sequence of given char values. This method is case-sensitive.

The index position of first character in a string is always starts with zero. If an element is not present in a string, it returns -1.

Syntax

These are the following methods used to search the position of an element.

Method	Description
indexOf(ch)	It returns the index position of char value passed with method.
indexOf(ch,index)	It start searching the element from the provided index value and then returns the index position of specified char value.
indexOf(str)	It returns the index position of first character of string passed with method.
indexOf(str,index)	It start searching the element from the provided index value and then returns the index position of first character of string.

Parameters

ch - It represent the single character to search like 'a'.

index - It represent the index position from where search starts.

str - It represent the string to search like "Java".

Return

Index of a particular character.

JavaScript String indexOf() method example

Let's see the various ways of searching the position of an element with help of simple examples.

Example 1

Here, we will print the position of a single character.

<script>
var web="Learn JavaScript on TheDeveloperBlog";
document.write(web.indexOf('a'));
</script>

Test it Now

Output:

Example 2

In this example, we will provide the index value from where the search starts.

<script>
var web="Learn JavaScript on TheDeveloperBlog";
document.write(web.indexOf('a',3));
</script>

Test it Now

Output:

Example 3

Here, we will print the position of a first character of string.

<script>
var web="Learn JavaScript on TheDeveloperBlog";
document.write(web.indexOf("Java"));
</script>

Test it Now

Output:

Example 4

In this example, we will provide the index value from where the search starts.

</script>
var web="Learn JavaScript on TheDeveloperBlog";
document.write(web.indexOf("Java",7));
</script>

Test it Now

Output:

Example 5

Here, we will try to search the element by changing its case-sensitivity.

<script>
var web="Learn JavaScript on TheDeveloperBlog";
document.write(web.indexOf("java"));
</script>

Test it Now

Output:

-1

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JavaScript String indexOf() Method

JavaScript String indexOf() method

Syntax

Parameters

Return

JavaScript String indexOf() method example

Example 1

Example 2

Example 3

Example 4

Example 5

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