This is not the same as being equal according to the == operator. The == operator applies various coercions to both sides (if they are not the same Type) before testing for equality (resulting in such behavior as "" == false being true), but Object.is doesn't coerce either value.
This is also not the same as being equal according to the === operator. The === operator (and the == operator as well) treats the number values -0 and +0 as equal and treats Number.NaN as not equal to NaN.
Object.is('foo', 'foo'); // true
Object.is(window, window); // true
Object.is('foo', 'foo'); // true
Object.is(window, window); // true
Object.is('foo', 'bar'); // false
Object.is([], []); // false
var test = { a: 1 };
Object.is(test, test); // true
Object.is(null, null); // true
// Special Cases
Object.is(0, -0); // false
Object.is(-0, -0); // true
Object.is(NaN, 0/0); // true