Skip to main content
Module

std/bytes/mod.ts>lastIndexOfNeedle

The Deno Standard Library
denoland/deno_std
Latest
function lastIndexOfNeedle
import { lastIndexOfNeedle } from "https://deno.land/std@0.224.0/bytes/mod.ts";

Returns the index of the last occurrence of the needle array in the source array, or -1 if it is not present.

The complexity of this function is O(source.length * needle.length).

Examples

Basic usage

import { lastIndexOfNeedle } from "https://deno.land/std@0.224.0/bytes/last_index_of_needle.ts";

const source = new Uint8Array([0, 1, 2, 1, 2, 1, 2, 3]);
const needle = new Uint8Array([1, 2]);
const notNeedle = new Uint8Array([5, 0]);

lastIndexOfNeedle(source, needle); // 5
lastIndexOfNeedle(source, notNeedle); // -1

Start index

import { lastIndexOfNeedle } from "https://deno.land/std@0.224.0/bytes/last_index_of_needle.ts";

const source = new Uint8Array([0, 1, 2, 1, 2, 1, 2, 3]);
const needle = new Uint8Array([1, 2]);

lastIndexOfNeedle(source, needle, 2); // 1
lastIndexOfNeedle(source, needle, 6); // 3

Defining a start index will begin the search at the specified index in the source array.

Parameters

source: Uint8Array

Source array to check.

needle: Uint8Array

Needle array to check for.

optional
start: number = [UNSUPPORTED]

Start index in the source array to begin the search. Defaults to the end of the array.

Returns

number

Index of the last occurrence of the needle array in the source array, or -1 if it is not present.