Investigate Object.is()

[chrisbolin]

The Object.is class method is very close to === but differs in two ways:

• NaN vs. NaN - === treats these as unequal, but Object.is treats them as equal
• +0 vs. 0 - === treats these as equal, but Object.is treats them as unequal

> Object.is(NaN, NaN)
true
> NaN === NaN
false
> Object.is(+0, -0)
false
> +0 === -0
true

Benefits

• A few unnecessary re-renders could probably be avoided if we treated NaN as equal to itself
• We could be more correct if we treated +0 and -0 as separate

Both of these are pretty minor cases

Downsides

This check doesn't come for free.

Benchmarks on node 8.3.0 using master, Object.is, and the MDN polyfill.

The native method is about 17% slower, and the polyfill is about 7.5% slower.

--- speed tests: generic usage ---

react-fast-compare x 175,552 ops/sec ±1.63% (87 runs sampled)
react-fast-compare-object-is x 146,104 ops/sec ±2.18% (85 runs sampled)
react-fast-compare-object-is-polyfill x 162,487 ops/sec ±1.62% (84 runs sampled)
  fastest: react-fast-compare

--- speed tests: generic and react ---

react-fast-compare x 140,986 ops/sec ±1.54% (85 runs sampled)
react-fast-compare-object-is x 122,360 ops/sec ±1.07% (89 runs sampled)
react-fast-compare-object-is-polyfill x 138,398 ops/sec ±1.42% (85 runs sampled)
  fastest: react-fast-compare,react-fast-compare-object-is-polyfill

Code for benchmarks is here: https://github.com/FormidableLabs/react-fast-compare/pull/9

[chrisbolin]

Current decision: don't use Object.is() or a polyfill; the performance losses are too much.