All files / bytes / concat.ts

// Copyright 2018-2025 the Deno authors. MIT license.
// This module is browser compatible.

import type { Uint8Array_ } from "./_types.ts";
export type { Uint8Array_ };

/**
 * Concatenate an array of byte slices into a single slice.
 *
 * @param buffers Array of byte slices to concatenate.
 * @returns A new byte slice containing all the input slices concatenated.
 *
 * @example Basic usage
 * ```ts
 * import { concat } from "@std/bytes/concat";
 * import { assertEquals } from "@std/assert";
 *
 * const a = new Uint8Array([0, 1, 2]);
 * const b = new Uint8Array([3, 4, 5]);
 *
 * assertEquals(concat([a, b]), new Uint8Array([0, 1, 2, 3, 4, 5]));
 * ```
 */
export function concat(buffers: Uint8Array[]): Uint8Array_ {
  let length = 0;
  for (const buffer of buffers) {
    length += buffer.length;
  }
  const output = new Uint8Array(length);
  let index = 0;
  for (const buffer of buffers) {
    output.set(buffer, index);
    index += buffer.length;
  }

  return output;
}