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22 lines
742 B
TypeScript
22 lines
742 B
TypeScript
// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
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// This module is browser compatible.
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/** Returns true if the prefix array appears at the start of the source array,
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* false otherwise.
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*
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* The complexity of this function is O(prefix.length).
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*
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* ```ts
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* import { startsWith } from "https://deno.land/std@$STD_VERSION/bytes/starts_with.ts";
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* const source = new Uint8Array([0, 1, 2, 1, 2, 1, 2, 3]);
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* const prefix = new Uint8Array([0, 1, 2]);
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* console.log(startsWith(source, prefix)); // true
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* ```
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*/
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export function startsWith(source: Uint8Array, prefix: Uint8Array): boolean {
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for (let i = 0, max = prefix.length; i < max; i++) {
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if (source[i] !== prefix[i]) return false;
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}
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return true;
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}
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