@instantdb/core
Version:
Instant's core local abstraction
75 lines • 2.32 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.default = weakHash;
/**
* Stable, non-cryptographic 64-bit hash.
*
* We aren't concerned with the hash being decoded.
*
* We _do_ want to make sure hashes remain the same, even
* when objects undergo serializing and deserializing.
*
* Inspired by cyrb53 (Math.imul + xxhash-style avalanche).
* https://stackoverflow.com/a/52171480
*
* @param {any} input - Value to hash
* @returns {string} - Hash in hex format
*/
function weakHash(input) {
const str = stableStringify(input);
let h1 = 0xdeadbeef ^ str.length;
let h2 = 0x41c6ce57 ^ str.length;
for (let i = 0; i < str.length; i++) {
const ch = str.charCodeAt(i);
h1 = Math.imul(h1 ^ ch, 2654435761);
h2 = Math.imul(h2 ^ ch, 1597334677);
}
h1 =
Math.imul(h1 ^ (h1 >>> 16), 2246822507) ^
Math.imul(h2 ^ (h2 >>> 13), 3266489909);
h2 =
Math.imul(h2 ^ (h2 >>> 16), 2246822507) ^
Math.imul(h1 ^ (h1 >>> 13), 3266489909);
return `${(h2 >>> 0).toString(16).padStart(8, '0')}${(h1 >>> 0)
.toString(16)
.padStart(8, '0')}`;
}
function stableStringify(input) {
if (input && typeof input.toJSON === 'function') {
return stableStringify(input.toJSON());
}
if (Array.isArray(input)) {
let out = '[';
for (let i = 0; i < input.length; i++) {
if (i > 0)
out += ',';
out += stableStringify(input[i]);
}
return out + ']';
}
if (input && typeof input === 'object') {
const keys = Object.keys(input);
keys.sort();
let out = '{';
let first = true;
for (let i = 0; i < keys.length; i++) {
const key = keys[i];
const value = input[key];
if (value === undefined)
continue;
if (!first)
out += ',';
out += JSON.stringify(key) + ':' + stableStringify(value);
first = false;
}
return out + '}';
}
if (input === undefined) {
return 'undefined';
}
if (typeof input === 'bigint') {
return `${input}n`;
}
return JSON.stringify(input) ?? String(input);
}
//# sourceMappingURL=weakHash.js.map