How to prevent modification in Object.prototype?

Question

I add some utils methods to Object class:

Object.prototype.doSomething = function() {
   // do something
};

And now I want to prevent any addition to Object.prototype, is it possible?

Answer 1

Yes, you can make the object non-extensible and make all of its properties read-only via Object.freeze.

Object.freeze(Object.prototype);

I'd test thoroughly after doing so. :-)

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Side note: I'd strongly recommend not using simple assignment to add properties to Object.prototype. Extending Object.prototype at all is usually not recommended, but if you're going to do it, make sure you make the new properties non-enumerable by using defineProperty:

Object.defineProperty(Object.prototype, "doSomething", {
    value: function () {
        // do something
    }
});