can be used to replace '==='. fixes some ES5 issues.

object.is.js

let notNum = NaN;

console.log( notNum === notNum );
// false
console.log( Object.is(notNum, notNum) )
// true

let amt = 0, total = -0;

console.log( amt === total )
// true
console.log( Object.is(amt, total) );
// false