Egal

Champions: (?)
Details: full proposal
Wiki: here

Exposes the internal SameValue algorithm as a function. It introduces the function as Object.is.

===

Main differences between === and Object.is are the way NaNs and (negative) zeroes are treated. A NaN is egal to another NaN and negative zeroes are not egal from other positive zeroes.

Object.is(0, -0); // false
Object.is(NaN, NaN); // true

0 === -0; // true
NaN === NaN; // false

Syntax

There is no new syntax for Object.is, obviously.

Polyfill

This is how you can define Object.is in es5:

Object.defineProperty(Object, 'is', {
  value: function(x, y) {
    if (x === y) {
      // 0 === -0, but they are not identical
      return x !== 0 || 1 / x === 1 / y;
    }

    // NaN !== NaN, but they are identical.
    // NaNs are the only non-reflexive value, i.e., if x !== x,
    // then x is a NaN.
    // isNaN is broken: it converts its argument to number, so
    // isNaN("foo") => true
    return x !== x && y !== y;
  },
  configurable: true,
  enumerable: false,
  writable: true
});