How to compare JavaScript objects obtained by parsing JSON?

Question

wtf1 = JSON.parse('{"asdf": "jkl"}');
wtf2 = JSON.parse('{"asdf": "jkl"}');

wtf1 == wtf2; // false
wtf1 === wtf2; // false

I’ve recently stumbled upon the above problem. This counter-intuitive situation makes it hard to, for example, find a specific object in an array deep in a JSON hierarchy.

Any way to somehow compare such objects?

Answer 1

For simple objects you can stringify them again (with ordered keys) and compare strings. For example:

var wtf1 = JSON.parse('{"a": "a", "b": "b"}');
var wtf2 = JSON.parse('{"b": "b", "a": "a"}');
var s1 =  JSON.stringify(wtf1, Object.keys(wtf1).sort());
var s2 =  JSON.stringify(wtf2, Object.keys(wtf2).sort());
console.log('wtf1 is equal to wtf2: ', (s1 == s2));

For nested objects with prototypes etc you should probably use _.isEqual or any other lib that provides deep equality test.

Note, that in general it's not trivial to correctly implement deep equality test for objects, it's not as simple as iterating and comparing keys/values. However, since the "objects were obtained by parsing JSON" you can skip most of complications and recursively stringify nested values.