// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.

/** Returns true if the prefix array appears at the start of the source array,
 * false otherwise.
 *
 * The complexity of this function is O(prefix.length).
 *
 * ```ts
 * import { startsWith } from "@std/bytes/starts_with";
 * const source = new Uint8Array([0, 1, 2, 1, 2, 1, 2, 3]);
 * const prefix = new Uint8Array([0, 1, 2]);
 * console.log(startsWith(source, prefix)); // true
 * ```
 */
export function startsWith(source: Uint8Array, prefix: Uint8Array): boolean {
  for (let i = 0, max = prefix.length; i < max; i++) {
    if (source[i] !== prefix[i]) return false;
  }
  return true;
}