createFastHashJS.js — react Source File

Source Code

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow
 */

// A pure JS implementation of a string hashing function. We do not use it for
// security or obfuscation purposes, only to create compact hashes. So we
// prioritize speed over collision avoidance. For example, we use this to hash
// the component key path used by useActionState for MPA-style submissions.
//
// In environments where built-in hashing functions are available, we prefer
// those instead. Like Node's crypto module, or Bun.hash. Unfortunately this
// does not include the web standard crypto API because those methods are all
// async. For our purposes, we need it to be sync because the cost of context
// switching is too high to be worth it.
//
// The most popular hashing algorithm that meets these requirements in the JS
// ecosystem is MurmurHash3, and almost all implementations I could find used
// some version of the implementation by Gary Court inlined below.

export function createFastHashJS(key: string): number {
  return murmurhash3_32_gc(key, 0);
}

/* eslint-disable prefer-const, no-fallthrough */

/**
 * @license
 *
 * JS Implementation of MurmurHash3 (r136) (as of May 20, 2011)
 *
 * Copyright (c) 2011 Gary Court
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

function murmurhash3_32_gc(key: string, seed: number): number {
  let remainder, bytes, h1, h1b, c1, c2, k1, i;

  remainder = key.length & 3; // key.length % 4
  bytes = key.length - remainder;
// ... (63 more lines)