Compare mishandles Dates

[DillonReddingW2G]

Using compare on an object with Date fields generates an add operation per character of the ISO date string, rather than comparing the Date as a whole.

Example

import { compare } from 'fast-json-patch';

const obj1 = { foo: new Date() };
const obj2 = { foo: new Date(obj1.foo.getTime() + 1)};
const diff = compare(obj1, obj2);
console.log(diff);

Output

[
  { op: 'add', path: '/foo/0', value: '2' },
  { op: 'add', path: '/foo/1', value: '0' },
  { op: 'add', path: '/foo/2', value: '2' },
  { op: 'add', path: '/foo/3', value: '5' },
  { op: 'add', path: '/foo/4', value: '-' },
  { op: 'add', path: '/foo/5', value: '0' },
  { op: 'add', path: '/foo/6', value: '2' },
  { op: 'add', path: '/foo/7', value: '-' },
  { op: 'add', path: '/foo/8', value: '1' },
  { op: 'add', path: '/foo/9', value: '3' },
  { op: 'add', path: '/foo/10', value: 'T' },
  { op: 'add', path: '/foo/11', value: '1' },
  { op: 'add', path: '/foo/12', value: '4' },
  { op: 'add', path: '/foo/13', value: ':' },
  { op: 'add', path: '/foo/14', value: '5' },
  { op: 'add', path: '/foo/15', value: '8' },
  { op: 'add', path: '/foo/16', value: ':' },
  { op: 'add', path: '/foo/17', value: '4' },
  { op: 'add', path: '/foo/18', value: '0' },
  { op: 'add', path: '/foo/19', value: '.' },
  { op: 'add', path: '/foo/20', value: '8' },
  { op: 'add', path: '/foo/21', value: '5' },
  { op: 'add', path: '/foo/22', value: '5' },
  { op: 'add', path: '/foo/23', value: 'Z' }
]

[sannnekk]

The same in my case. However, I realized that I was comparing a normal object with a Proxy to generate patches, deproxifying it partially resolved the issue. However, now I get this (Dates are the same but it still tries to replace them):

 {
    "op": "test",
    "path": "/subject/updatedAt",
    "value": "2024-08-29T23:27:35.579Z"
  },
  {
    "op": "replace",
    "path": "/subject/updatedAt",
    "value": "2024-08-29T23:27:35.579Z"
  },