react-fast-memo

A faster React.memo(). Use it as a direct replacement. Also includes fast object comparison functions.

$3

``javascript
import fastMemo from 'react-fast-memo'

const MemoizedComponent = fastMemo(function Component(props) {
return (



)
})
`

These comparison functions are also included:

`javascript
import { fastCompare, fastCompareUnsafe } from 'react-fast-memo'

// fastCompare is for general and correct nullable-objects comparison
console.log(fastCompare(
{ a: 1, b: undefined },
{ a: 1 },
))
// => false

// fastCompareUnsafe is optimized for one case: non-nullable objects
// where either:
// - field: undefined is equivalent to not having the field.
// - you can 100% guarantee that objects have the same shape
console.log(fastCompareUnsafe(
{ a: 1, b: undefined },
{ a: 1, c: undefined },
))
// => true

`

If you never use the pattern 'key' in props in your codebase and are ok with using fastCompareUnsafe for
top-of-the-line performance, you can use that version:


`javascript
import { fastMemoUnsafe } from 'react-fast-memo'
`

$3

In least performant to most performant order. Each function is benchmarked for objects that are equal and unequal.
The full results here are for V8, and I have added partial results for JSC and SpiderMonkey after. Suprisingly, in JSC
the safe version is the fastest one.

Runnable benchmark code is in the ./benchmark folder, and consist of comparing two 8-keys monomorphic objects together
in a 1,000,000 iteration loop, in two cases: equal values, and unequal values (one differing value). Results are in
milliseconds

`jsonc
// V8
{
"fbjs/lib/shallowEqual:equal:monomorphic": { t: 1339.67, stddev: 2.35},
"fbjs/lib/shallowEqual:unequal:monomorphic": { t: 1274.33, stddev: 7.58},

"fast-shallow-equal:equal:monomorphic": { t: 1228.33, stddev: 36.44},
"fast-shallow-equal:unequal:monomorphic": { t: 1174.33, stddev: 2.62},

"react:equal:monomorphic": { t: 1240, stddev: 1.41},
"react:unequal:monomorphic": { t: 1229.67, stddev: 4.71},

"fast-equals.shallowEqual:equal:monomorphic": { t: 1261.33, stddev: 42.67},
"fast-equals.shallowEqual:unequal:monomorphic": { t: 333.33, stddev: 2.05},

"shallowequal:equal:monomorphic": { t: 1153, stddev: 67.23 },
"shallowequal:unequal:monomorphic": { t: 1188, stddev: 29.06},

"romgrk-fastCompare:equal:monomorphic": { t: 859.67, stddev: 3.39},
"romgrk-fastCompare:unequal:monomorphic": { t: 769.33, stddev: 2.05},

"hughsk/shallow-equals:equal:monomorphic": { t: 592.33, stddev: 41.96},
"hughsk/shallow-equals:unequal:monomorphic": { t: 563.33, stddev: 4.18},
// This one is faster than our safe one, but it uses === for comparison
// instead of Object.is, it is therefore incorrect because NaN !== NaN
// due to the unsound semantics of === in float comparison.

"romgrk-fastCompareUnsafe:equal:monomorphic": { t: 515.67, stddev: 1.24},
"romgrk-fastCompareUnsafe:unequal:monomorphic": { t: 455.67, stddev: 7.31},
}
`

`jsonc
// JSC
{
"react:equal:monomorphic": { t: 401, stddev: 25.152865973217974 },
"react:unequal:monomorphic": { t: 415.33, stddev: 3.39934634239519 },

"hughsk/shallow-equals:equal:monomorphic": { t: 297, stddev: 14.236104336041748 },
"hughsk/shallow-equals:unequal:monomorphic": { t: 189.33, stddev: 2.0548046676563256 },

"romgrk-fastCompare:equal:monomorphic": { t: 199.67, stddev: 6.847546194724712 },
"romgrk-fastCompare:unequal:monomorphic": { t: 128.67, stddev: 1.247219128924647 },

"romgrk-fastCompareUnsafe:equal:monomorphic": { t: 313.67, stddev: 30.26916289265731 },
"romgrk-fastCompareUnsafe:unequal:monomorphic": { t: 244.67, stddev: 3.8586123009300755 },
}
`

`jsonc
// SpiderMonkey
{
"react:equal:monomorphic": { t: 975.33, stddev: 1.24721912892464 },
"react:unequal:monomorphic": { t: 1073, stddev: 13.49073756323204 },

"hughsk/shallow-equals:equal:monomorphic": { t: 661.33, stddev: 50.5459087255228 },
"hughsk/shallow-equals:unequal:monomorphic": { t: 509, stddev: 22.01514630127782 },

"romgrk-fastCompare:equal:monomorphic": { t: 506.33, stddev: 3.3993463423951 },
"romgrk-fastCompare:unequal:monomorphic": { t: 503.67, stddev: 3.681787005729087 },

"romgrk-fastCompareUnsafe:equal:monomorphic": { t: 468.33, stddev: 6.18241233033046 },
"romgrk-fastCompareUnsafe:unequal:monomorphic": { t: 466.67, stddev: 3.09120616516523 },
}
``