How to use array.lastIndexOf() method In Javascript

Method 3: Using Binary Search

In this approach, we will use array.lastIndexOf() method. 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)

Example: In this example, we will use arr.indexOf() method to find the last occurrence of target element

Javascript

// Input array 
const arr = [1, 2, 3, 4, 5, 5, 5, 6, 6, 7, 8, 8, 9]; 
  
// Target element 
const target = 8; 
  
// Get first index of element using indexOf method() 
const outputIndex = arr.lastIndexOf(target); 
  
// If not found display output 
if (outputIndex === -1) 
    console.log(target + " is not present in the given"); 
else { 
    console.log( 
        "Last index of " + 
        target + 
        " is at index: " + 
        outputIndex 
    ); 
}

Output

Last index of 8 is at index: 11

JavaScript Program to find the Index of Last Occurrence of Target Element in Sorted Array

In this article, we will see the JavaScript program to get the last occurrence of a number in a sorted array. We have the following methods to get the last occurrence of a given number in the sorted array.