Identical to `buf.indexOf()`, except the last occurrence of `value` is found rather than the first occurrence. ```js import { Buffer } from 'node:buffer'; const buf = Buffer.from('this buffer is a buffer'); console.log(buf.lastIndexOf('this')); // Prints: 0 console.log(buf.lastIndexOf('buffer')); // Prints: 17 console.log(buf.lastIndexOf(Buffer.from('buffer'))); // Prints: 17 console.log(buf.lastIndexOf(97)); // Prints: 15 (97 is the decimal ASCII value for 'a') console.log(buf.lastIndexOf(Buffer.from('yolo'))); // Prints: -1 console.log(buf.lastIndexOf('buffer', 5)); // Prints: 5 console.log(buf.lastIndexOf('buffer', 4)); // Prints: -1 const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'utf16le'); console.log(utf16Buffer.lastIndexOf('\u03a3', undefined, 'utf16le')); // Prints: 6 console.log(utf16Buffer.lastIndexOf('\u03a3', -5, 'utf16le')); // Prints: 4 ``` If `value` is not a string, number, or `Buffer`, this method will throw a `TypeError`. If `value` is a number, it will be coerced to a valid byte value, an integer between 0 and 255. If `byteOffset` is not a number, it will be coerced to a number. Any arguments that coerce to `NaN`, like `{}` or `undefined`, will search the whole buffer. This behavior matches [`String.prototype.lastIndexOf()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/lastIndexOf). ```js import { Buffer } from 'node:buffer'; const b = Buffer.from('abcdef'); // Passing a value that's a number, but not a valid byte. // Prints: 2, equivalent to searching for 99 or 'c'. console.log(b.lastIndexOf(99.9)); console.log(b.lastIndexOf(256 + 99)); // Passing a byteOffset that coerces to NaN. // Prints: 1, searching the whole buffer. console.log(b.lastIndexOf('b', undefined)); console.log(b.lastIndexOf('b', {})); // Passing a byteOffset that coerces to 0. // Prints: -1, equivalent to passing 0. console.log(b.lastIndexOf('b', null)); console.log(b.lastIndexOf('b', [])); ``` If `value` is an empty string or empty `Buffer`, `byteOffset` will be returned.

Parameters

value:

string
| number
| Uint8Array

What to search for.

optional

byteOffset: number = buf.length - 1

Where to begin searching in `buf`. If negative, then offset is calculated from the end of `buf`.

optional

encoding: BufferEncoding = 'utf8'

If `value` is a string, this is the encoding used to determine the binary representation of the string that will be searched for in `buf`.

Return Type

number

The index of the last occurrence of `value` in `buf`, or `-1` if `buf` does not contain `value`.