A deterministic object hashing algorithm for Node.js.
npm install deterministic-object-hashJSON.stringify on two objects that are deeply equal does not lead to the same output string. Instead the keys are ordered in the same order that they were added. This leads to two objects that are deeply equal being hashed to different values.``typescript
import { createHash } from "crypto";
import { isEqual } from "lodash";
const obj1: Record
obj1['a'] = 'x';
obj1['b'] = 'y';
obj1['c'] = 'z';
const obj2: Record
obj2['c'] = 'z';
obj2['b'] = 'y';
obj2['a'] = 'x';
isEqual(obj1, obj2);
// -> true
const string1 = JSON.stringify(obj1);
// -> {"a":"x","b":"y","c":"z"}
const string2 = JSON.stringify(obj2);
// -> {"c":"z","b":"y","a":"x"}
createHash('sha1').update(string1).digest('hex');
// -> ff75fe071d236ce309c15d5636ecaa86c0519ebc
createHash('sha1').update(string2).digest('hex');
// -> 2e53bac865f7be77c8e10cd86d737fbbf259ed37
`
`typescript
import deterministicHash from 'deterministic-object-hash';
const objA = { a: 'x', arr: [1,2,3,4], b: 'y' };
const objB = { b: 'y', a: 'x', arr: [1,2,3,4] };
await deterministicHash({
c: [ objA, objB ],
b: objA,
e: objB,
f: ()=>{ Math.random(); },
g: Symbol('Unique identity'),
h: new Error('AHHH')
});
// -> 4c57bcb76498dca7b98ef9747c8f1e7f10c30388
await deterministicHash({
h: new Error('AHHH'),
e: objB,
g: Symbol('Unique identity'),
b: objA,
f: ()=>{ Math.random(); },
c: [ objA, objB ]
});
// -> 4c57bcb76498dca7b98ef9747c8f1e7f10c30388
`
A hash algorithm can be passed as the second argument. This takes any value that is valid for webcrypto.subtle.digest. The default is SHA-1. \Hash.digest
A digest format can be passed as the third argument. This takes any value that is valid for . The default is hex.
`typescript`
await deterministicHash('value', 'SHA-1');
// -> efede6000ad4e1ff258a38866c71aa351d3c01f6
await deterministicHash('value', 'SHA-256', 'hex');
// -> a0b7821a11db531982044ca5ca2e788e2d749d6b696cd3aa4172342f584f2ee1
await deterministicHash('value', 'SHA-512', 'base64');
// -> 514CuHw/31qqUH2waqaqhKSMvLYH/YdZeRI4QqDBwhKbUk0/3mxhv4NUubXIl5Dm2k0VpU6ZZkmunEb10RngfQ==
Due to their nature, WeakSet and WeakMap are not enumerable. As a result there is no way to know what is in a WeakSet/WeakMap unless we are told.