How to use lastIndexOf() Method In Javascript
The lastIndexOf() method in JavaScript is used to find the index of the last occurrence of a specified substring in a string. It searches the string from the end to the beginning and returns the index of the last occurrence of the substring, or -1 if the substring is not found.
Syntax:
str.lastIndexOf(searchValue , index)
Example: In this example, we find the last occurrence index of the substring “Computer” in the text. It displays the index if found; otherwise, indicates absence.
const text = "w3wiki, A Computer science Portal.";
// Substring to search for
const substring = "Computer";
// Using lastIndexOf() method
const lastIndex = text.lastIndexOf(substring);
if (lastIndex !== -1) {
console.log(`Last occurrence of '
${substring}
' found at index ${lastIndex}`);
} else {
console.log(
`'${substring}' not found in the text.`);
}
Output
Last occurrence of ' Computer ' found at index 17
JavaScript Program to Find the Index of the Last Occurrence of a Substring in a String
Finding the index of the last occurrence of a substring in a string is a common task in JavaScript. The last occurrence of a substring in a string in JavaScript refers to finding the final position where a specified substring appears within a given string. We may want to know the position of the last occurrence of a specific substring within a given string.
There are several methods that can be used to find the index of the last occurrence of a substring in a string in JavaScript, which are listed below:
Table of Content
- Using lastIndexOf() Method
- Using Regular Expression
- Using split() and pop()
- Using a Loop
- Using Array.prototype.reduceRight() Method
We will explore all the above methods along with their basic implementation with the help of examples.