webpack/lib/util/nonNumericOnlyHash.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Ivan Kopeykin @vankop
*/

"use strict";

/** @typedef {import("./Hash")} Hash */

const A_CODE = "a".charCodeAt(0);

/**
 * Returns hash that has at least one non numeric char.
 * @param {string} hash hash
 * @param {number} hashLength hash length
 * @returns {string} returns hash that has at least one non numeric char
 */
const nonNumericOnlyHash = (hash, hashLength) => {
	if (hashLength < 1) return "";
	const slice = hash.slice(0, hashLength);
	if (/[^\d]/.test(slice)) return slice;
	return `${String.fromCharCode(
		A_CODE + (Number.parseInt(hash[0], 10) % 6)
	)}${slice.slice(1)}`;
};

/**
 * Digests a hash and truncates it to a content-hash string (non-numeric first char).
 * @param {Hash} hash hash
 * @param {string} hashDigest digest encoding
 * @param {number} hashDigestLength hash length
 * @returns {string} content hash string
 */
const digestNonNumericOnly = (hash, hashDigest, hashDigestLength) =>
	nonNumericOnlyHash(hash.digest(hashDigest), hashDigestLength);

/**
 * Digests a hash, returning both the truncated content-hash string and the full
 * (untruncated) digest, so `[contenthash:<digest>]` can re-encode from full entropy.
 * @param {Hash} hash hash
 * @param {string} hashDigest digest encoding
 * @param {number} hashDigestLength hash length
 * @returns {[string, string]} content hash string and full digest
 */
const digestNonNumericOnlyWithFull = (hash, hashDigest, hashDigestLength) => {
	const full = /** @type {string} */ (hash.digest(hashDigest));
	return [nonNumericOnlyHash(full, hashDigestLength), full];
};

module.exports = nonNumericOnlyHash;
module.exports.digestNonNumericOnly = digestNonNumericOnly;
module.exports.digestNonNumericOnlyWithFull = digestNonNumericOnlyWithFull;