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document is part of browser api but still what if I want to override it though is there a way to force so as this triggers error

  var document = {
      f: function() {
          alert('o')
      }
  }

  document.f();

about 4 years ago · Juan Pablo Isaza

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Accepted Answer · 2022-07-11T09:58:55.172Z

Not on the top level. In Chrome, for example, window.document is a nonconfigurable getter that returns the document:

console.log(Object.getOwnPropertyDescriptor(window, 'document'));

Since it's non-configurable, it can't be overwritten with anything else.

And you can't declare a new top-level identifier named document either, since it already exists. Use strict mode to make the error explicit:

'use strict';
const document = 'foo';

But you can declare a new variable named document inside an IIFE (so it's not on the top level).

(() => {
  var document = {
    f: function() {
      alert('o')
    }
  }

  document.f();
})();