The JavaScript Array lastIndexOf() Method is used to find the index of the last occurrence of the search element provided as the argument to the function.

Syntax: 

array.lastIndexOf(element, start)

Parameters:

This method accepts two parameters as mentioned above and described below: 

• element: This parameter holds the element whose index will be returned.
• 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 last occurrence of the element. If the element cannot be found in the array, then this method returns -1.

Example 1: Below is an example of the Array lastIndexOf() method. 

let name = ['gfg', 'cse', 'geeks', 'portal'];
a = name.lastIndexOf('gfg')

// Printing result of method
console.log(a);

Output: 

0

Example 2: In this example, the method will be searched for element 2 in that array and return that element index. 

// Taking input as an array A
// having some elements.
let A = [1, 2, 3, 4, 5];

// lastIndexOf() method is called to
// test whether the searching element
// is present in given array or not.
a = A.lastIndexOf(2)

// Printing result of method.
console.log(a);

Output: 

1

Example 3: In this example, the method will search for the element 9 in that array if not found then return -1. 

// Taking input as an array A
// having some elements.
let name = ['gfg', 'cse', 'geeks', 'portal'];

// lastIndexOf() method is called to
// test whether the searching element
// is present in given array or not.
a = name.lastIndexOf('cat')

// Printing result of method
console.log(a);

Output: 

-1

We have a complete list of Javascript Array methods, to check those please go through this Javascript Array Complete reference article.

Supported Browsers:

The browsers supported by JavaScript Array lastIndexOf() method are listed below: 

• Google Chrome 38
• Microsoft Edge 12
• Mozilla Firefox 28
• Safari 8
• Opera 25