Below is the example of the Array indexOf() method.

• Example:
  
  

  
  
  

  <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)

Paramaters: 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 indesx.

  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:

Output:

1

Program 2:

Output:

-1

Supported Browsers: The browsers supported by JavaScript Array indexOf() method are listed below:

• Google Chrome
• Microsoft Edge 9.0
• Mozilla Firefox 1.5
• Safari
• Opera