Preventing object comparision in javascript

Question

Is there a way in JS to prevent object comparision?

Lets say i have:

function Person(data) {
  var that = {};
  that.name = data.name;
  return that;
}

let p = new Person({'name':'John'})

Now i want this to throw an error:

p == 2

I don't think so. What would be the added benefit or use case? — Emiel Zuurbier, May 11 '21 at 22:43
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/instanceof — Niloct, May 11 '21 at 22:43
Do you want to throw exceptions only when comparing against numbers, or when comparing against anything? — Bergi, May 11 '21 at 22:45
@EmielZuurbier use case is preventing other users of code base of making a mistake, since my example would always return false. — Vladimir Gromes, May 11 '21 at 22:46
@VladimirGromes That's not possible. Also I doubt that you really *want* `p == p` to throw an exception instead of returning `true`. — Bergi, May 11 '21 at 22:50
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/valueOf — loop, May 11 '21 at 22:50

Robby Cornelissen · Accepted Answer · 2021-05-11T22:52:03.647

The only way I can think of is by relying on the fact that the comparison operator (==) uses string conversion to compare operands of different types:

function Person(data) {
  var that = {};
  that.name = data.name;
  return that;
}

let p = new Person({'name':'John'});

p.toString = function() {
  throw 'Error!';
}

p == 2

Of course, that would cause errors for all other string conversion of said object too, and it wouldn't work for the strict comparison operator (===).

Preventing object comparision in javascript

1 Answers1

Linked