Why does {} == {} equals false? [duplicate]

Question

Short question about JavaScript. I tried to execute {} == {} in JavaScript and expected to get true, but it didn't and I want to understand why. Shouldn't {} == {} return true and {} === {} return false?

Answer 1

Because == and === check if the two compared variables are references to the same object, not whether they are identical in value.

Thus a two variables internally referencing each other or a third variable are both == and ===, two new instances of an object are not.

To check if two objects are identical, you could JSON.stringify() them and check whether or not the results are the same.

Most common libraries for JavaScript contain a function to compare two objects, in vanilla JS you can make such a function for yourself:

Object.compare = function(obj1, obj2) {
  if (obj1 && obj2) return JSON.stringify(obj1) === JSON.stringify(obj2)
}

console.log(
    Object.compare({foo:"bar"}, {foo:"bar"})
);