Node.js Buffer.lastIndexOf() Method

Buffer is a temporary memory storage that stores the data when it is being moved from one place to another. It is like an array of integers. The Buffer.lastIndexOf() Method checks for a given value in the buffer and returns its index where it is present. If the same value is present more than once, then it returns the last index where the value is present. 

Syntax:

Buffer.lastIndexOf( value, byteOffset, encoding )

Parameters: This method accepts three parameters as mentioned above and described below:

• value: It specifies the data that need to be searched in the buffer.
• byteOffset: The index from which you need to start searching the buffer. Its default value is 0.
• encoding: It holds a string value that determines the binary representation of the string that search in the buffer. Its default value is utf8.

Return Value: This method returns an integer value representing the index value. Below examples illustrate the use of Buffer.lastIndexOf() method in Node.js: 

Example 1: In this example, we will see the use of Buffer.lastIndexOf() Method

javascript

// Node program to demonstrate the
// Buffer.lastIndexOf() Method

const buffer = Buffer.from('GeeksForGeeks');

console.log(buffer.lastIndexOf('G'));

Output

8

Example 2: In this example, we will see the use of Buffer.lastIndexOf() Method

javascript

// Node program to demonstrate the
// Buffer.lastIndexOf() Method

const buffer = Buffer.from('GeeksForGeeks');

console.log(buffer.lastIndexOf(101));
// Prints : 10
// 101 is the ascii value of 'e'
// e occurs last at index 10

console.log(buffer.lastIndexOf('computer portal'));
//Prints : -1
//as it is not present in the given value

Output: 

10
-1

Note: The above program will compile and run by using the node index.js command. Reference: https://nodejs.org/api/buffer.html#buffer_buf_lastindexof_value_byteoffset_encoding