Jump to headingBuffer.lastIndexOf(): numberIdentical to buf.indexOf(), except the last occurrence of value is found
rather than the first occurrence.
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().
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 Jump to heading
Jump to headingvalue: string
| number
| Uint8ArrayWhat to search for.
Jump to headingbyteOffset: number = buf.length - 1Where to begin searching in buf. If negative, then offset is calculated from the end of buf.
Jump to headingencoding: 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 Jump to heading
numberThe index of the last occurrence of value in buf, or -1 if buf does not contain value.