JavaScript Array indexOf() Method
Below is the example of the Array indexOf() method.
- Example:
javascript
<script> var name = [ 'gfg' , 'cse' , 'geeks' , 'portal' ]; a = name.indexOf( 'gfg' ) // Printing result of method document.write(a); </script> |
- Output:
0
The arr.indexOf() method is used to find the index of the first occurrence of the search element provided as the argument to the method.
Syntax:
array.indexOf(element, start)
Parameters: This method accepts two parameters as mentioned above and described below:
- element: This parameter holds the element which index will be return.
- start: This parameter is optional and it holds the starting point of the array, where to begin the search the default value is 0.
Return value: This method returns the index of the first occurrence of the element. If the element cannot be found in the array, then this method returns -1.
Below examples illustrate the Array indexOf() method in JavaScript:
- Example 1: In this example the method will searched for the element 2 in that array return that element index.
Input : [1, 2, 3, 4, 5].indexOf(2); Output: 1
- Example 2: In this example the method will searched for the element 9 in that array if not found then return -1.
Input : [1, 2, 3, 4, 5].indexOf(9); Output: -1
Code for the above method is provided below:
Program 1:
javascript
<script> // Taking input as an array A // having some elements. var A = [ 1, 2, 3, 4, 5 ]; // indexOf() method is called to // test whether the searching element // is present in given array or not. a = A.indexOf(2) // Printing result of method. document.write(a); </script> |
Output:
1
Program 2:
javascript
<script> // Taking input as an array A // having some elements. var name = [ 'gfg' , 'cse' , 'geeks' , 'portal' ]; // indexOf() method is called to // test whether the searching element // is present in given array or not. a = name.indexOf( 'cat' ) // Printing result of method document.write(a); </script> |
Output:
-1
Supported Browsers: The browsers supported by JavaScript Array indexOf() method are listed below:
- Google Chrome 1 and above
- Edge 12 and above
- Firefox 1.5 and above
- Internet Explorer 9 and above
- Opera 9.5 and above
- Safari 3 and above