Assigning Object.prototype causes issues with jQuery

Question

I'm trying to assign a function to Object.prototype.equals similar to what's done in Object comparison in JavaScript. The function works perfectly, but whenever I have jQuery about, I get errors like:

name.replace is not a function

referring to line 6490 in jquery-1.6.1.js.

Does anyone know why this could be happening?

Even if I remove the function body, just returning true, I get the same issue. — josef.van.niekerk, Jun 13 '11 at 15:26
http://stackoverflow.com/questions/1827458/prototyping-object-in-javascript-breaks-jquery — Junior Mayhé, Sep 23 '12 at 14:11

Raynos · Accepted Answer · 2011-06-13T15:33:17.243

Don't monkey patch Object.prototype.

Object.prototype.replace = "lol";

for (var i in { "bar": 42 }) {
  alert(i);
}
// "bar"
// "replace" :(

Basically for ... in loops iterate over all properties in an object including ones defined on the prototype. This is why it's really bad practice to extend or change Object.prototype.

Some people also go as far as "Don't monkey patch Array, String, Function, ...".

You should never mess with the Object.prototype. The rest of the native prototypes are a style choice.

Define your function on Object.

Object.replace = function() { ... };

var o = Object.replace(p);

ES5:

With ecmascript 5 you can set properties as non-enumerable

Object.defineProperty(Object.prototype, "replace", {
  value: function() { }
});

Yeah, I think I'm just gonna create a standalone function. – josef.van.niekerk Jun 13 '11 at 15:31 — josef.van.niekerk, Jun 13 '11 at 15:31

Assigning Object.prototype causes issues with jQuery

1 Answers1