The indexOf method in JavaScript is utilized to locate the position of a specific character or substring within a sequence of characters. It is important to note that this method is case-sensitive.
The index of the initial character in a string always begins at zero. If a character is absent from the string, the function returns -1.
Syntax
The subsequent techniques are employed to locate the position of a specific 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 - This signifies the individual character that you are looking for, such as 'a'.
index - It signifies the starting index position from which the search initiates.
str - This denotes the string that you are looking for, such as "Java".
Return
Index of a particular character.
JavaScript String indexOf method example
Let us explore the different methods to locate the position of an element through straightforward examples.
Example 1
In this section, we will display the location of an individual character.
<script>
var web="Learn JavaScript on Example";
document.write(web.indexOf('a'));
</script>
Output:
Example 2
In this illustration, we will specify the index position from which the search will commence.
<script>
var web="Learn JavaScript on Example";
document.write(web.indexOf('a',3));
</script>
Output:
Example 3
In this section, we will display the index of the initial character in a given string.
<script>
var web="Learn JavaScript on Example";
document.write(web.indexOf("Java"));
</script>
Output:
Example 4
In this instance, we will specify the index position from which the search will commence.
</script>
var web="Learn JavaScript on Example";
document.write(web.indexOf("Java",7));
</script>
Output:
Example 5
In this section, we will attempt to locate the element by altering its case sensitivity.
<script>
var web="Learn JavaScript on Example";
document.write(web.indexOf("java"));
</script>
Output: