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react-fast-compare

(★ 1,666)

fastest deep equal comparison for React

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Download Latest Version (.zip)

- config.json
- - ci.yml
  - release.yml
- pull_request_template.md
- benchmarking.png
- index.js
- - browser.spec.js
  - index.js
  - karma.conf.ie.js
  - karma.conf.js
- - advanced.spec.js
  - basics.spec.js
  - tests.js
- - sample-react-redux-usage.tsx
  - sample-usage.tsx
  - tsconfig.json
- .eslintrc.yml
- mocha.opts
.eslintignore
.eslintrc.yml
.gitignore
CHANGELOG.md
CONTRIBUTING.md
index.d.ts
index.js
LICENSE
package.json
react-fast-compare-Hero.png
README.md
tsconfig.json
yarn.lock

# Installation Guide

1. Get the code

git clone https://github.com/FormidableLabs/react-fast-compare

Downloads the entire project code from GitHub to your computer.

cd react-fast-compare

Moves into the project folder you just downloaded.

2. Node.js

Easy Recommended

Prerequisites

Git Needed to download the project code from GitHub.
Node.js Node.js must be installed to use npm. The LTS version is recommended.

$ yarn add react-fast-compare

Type this command into your terminal and run it.

$ npm install react-fast-compare

Downloads and installs the libraries listed in package.json.

$ yarn install

Downloads and installs the libraries listed in package.json.

$ yarn run benchmark

Type this command into your terminal and run it.

✅ After running the command, open the address shown in the terminal (usually something like http://localhost:3000) in your browser.

Pulled directly from this repo's README.

// repository documentation

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[![React Fast Compare — Formidable, We build the modern web](https://raw.githubusercontent.com/FormidableLabs/react-fast-compare/master/react-fast-compare-Hero.png)](https://formidable.com/open-source/)

[![Downloads][downloads_img]][npm_site]
[![Bundle Size][bundle_img]](https://raw.githubusercontent.com/FormidableLabs/react-fast-compare/master/)
[![GH Actions Status][actions_img]][actions_site]
[![Coverage Status][cov_img]][cov_site]
[![npm version][npm_img]][npm_site]
[![Maintenance Status][maintenance_img]](https://raw.githubusercontent.com/FormidableLabs/react-fast-compare/master/)

The fastest deep equal comparison for React. Very quick general-purpose deep
comparison, too. Great for `React.memo` and `shouldComponentUpdate`.

This is a fork of the brilliant
[fast-deep-equal](https://github.com/epoberezkin/fast-deep-equal) with some
extra handling for React.

![benchmark chart](https://raw.githubusercontent.com/FormidableLabs/react-fast-compare/master/assets/benchmarking.png "benchmarking chart")

(Check out the [benchmarking details](#benchmarking-this-library).)

## Install

```sh
$ yarn add react-fast-compare
# or
$ npm install react-fast-compare
```

## Highlights

- ES5 compatible; works in node.js (0.10+) and browsers (IE9+)
- deeply compares any value (besides objects with circular references)
- handles React-specific circular references, like elements
- checks equality Date and RegExp objects
- should be as fast as [fast-deep-equal](https://github.com/epoberezkin/fast-deep-equal) via a single unified library, and with added guardrails for circular references.
- small: under 660 bytes minified+gzipped

## Usage

```jsx
const isEqual = require("react-fast-compare");

// general usage
console.log(isEqual({ foo: "bar" }, { foo: "bar" })); // true

// React.memo
// only re-render ExpensiveComponent when the props have deeply changed
const DeepMemoComponent = React.memo(ExpensiveComponent, isEqual);

// React.Component shouldComponentUpdate
// only re-render AnotherExpensiveComponent when the props have deeply changed
class AnotherExpensiveComponent extends React.Component {
  shouldComponentUpdate(nextProps) {
    return !isEqual(this.props, nextProps);
  }
  render() {
    // ...
  }
}
```

## Do I Need `React.memo` (or `shouldComponentUpdate`)?

> What's faster than a really fast deep comparison? No deep comparison at all.

—This Readme

Deep checks in `React.memo` or a `shouldComponentUpdate` should not be used blindly.
First, see if the default
[React.memo](https://reactjs.org/docs/react-api.html#reactmemo) or
[PureComponent](https://reactjs.org/docs/react-api.html#reactpurecomponent)
will work for you. If it won't (if you need deep checks), it's wise to make
sure you've correctly indentified the bottleneck in your application by
[profiling the performance](https://reactjs.org/docs/optimizing-performance.html#profiling-components-with-the-chrome-performance-tab).
After you've determined that you _do_ need deep equality checks and you've
identified the minimum number of places to apply them, then this library may
be for you!

## Benchmarking this Library

The absolute values are much less important than the relative differences
between packages.

Benchmarking source can be found
[here](https://github.com/FormidableLabs/react-fast-compare/blob/master/benchmark/index.js).
Each "operation" consists of running all relevant tests. The React benchmark
uses both the generic tests and the react tests; these runs will be slower
simply because there are more tests in each operation.

The results below are from a local test on a laptop _(stats last updated 6/2/2020)_:

### Generic Data

```
react-fast-compare x 177,600 ops/sec ±1.73% (92 runs sampled)
fast-deep-equal x 184,211 ops/sec ±0.65% (87 runs sampled)
lodash.isEqual x 39,826 ops/sec ±1.32% (86 runs sampled)
nano-equal x 176,023 ops/sec ±0.89% (92 runs sampled)
shallow-equal-fuzzy x 146,355 ops/sec ±0.64% (89 runs sampled)
  fastest: fast-deep-equal
```

`react-fast-compare` and `fast-deep-equal` should be the same speed for these
tests; any difference is just noise. `react-fast-compare` won't be faster than
`fast-deep-equal`, because it's based on it.

### React and Generic Data

```
react-fast-compare x 86,392 ops/sec ±0.70% (93 runs sampled)
fast-deep-equal x 85,567 ops/sec ±0.95% (92 runs sampled)
lodash.isEqual x 7,369 ops/sec ±1.78% (84 runs sampled)
  fastest: react-fast-compare,fast-deep-equal
```

Two of these packages cannot handle comparing React elements, because they
contain circular reference: `nano-equal` and `shallow-equal-fuzzy`.

### Running Benchmarks

```sh
$ yarn install
$ yarn run benchmark
```

## Differences between this library and `fast-deep-equal`

`react-fast-compare` is based on `fast-deep-equal`, with some additions:

- `react-fast-compare` has `try`/`catch` guardrails for stack overflows from undetected (non-React) circular references.
- `react-fast-compare` has a _single_ unified entry point for all uses. No matter what your target application is, `import equal from 'react-fast-compare'` just works. `fast-deep-equal` has multiple entry points for different use cases.

This version of `react-fast-compare` tracks `fast-deep-equal@3.1.1`.

## Bundle Size

There are a variety of ways to calculate bundle size for JavaScript code.
You can see our size test code in the `compress` script in
[`package.json`](https://github.com/FormidableLabs/react-fast-compare/blob/master/package.json).
[Bundlephobia's calculation](https://bundlephobia.com/result?p=react-fast-compare) is slightly higher,
as they [do not mangle during minification](https://github.com/pastelsky/package-build-stats/blob/v6.1.1/src/getDependencySizeTree.js#L139).

## License

[MIT](https://github.com/FormidableLabs/react-fast-compare/blob/readme/LICENSE)

## Contributing

Please see our [contributions guide](./CONTRIBUTING.md).

## Maintenance Status

**Active:** Formidable is actively working on this project, and we expect to continue for work for the foreseeable future. Bug reports, feature requests and pull requests are welcome.

[actions_img]: https://github.com/FormidableLabs/react-fast-compare/actions/workflows/ci.yml/badge.svg
[actions_site]: https://github.com/formidablelabs/react-fast-compare/actions/workflows/ci.yml
[cov_img]: https://codecov.io/gh/FormidableLabs/react-fast-compare/branch/master/graph/badge.svg
[cov_site]: https://codecov.io/gh/FormidableLabs/react-fast-compare
[npm_img]: https://badge.fury.io/js/react-fast-compare.svg
[npm_site]: http://badge.fury.io/js/react-fast-compare
[appveyor_img]: https://ci.appveyor.com/api/projects/status/github/formidablelabs/react-fast-compare?branch=master&svg=true
[appveyor_site]: https://ci.appveyor.com/project/FormidableLabs/react-fast-compare
[bundle_img]: https://img.shields.io/badge/minzipped%20size-656%20B-flatgreen.svg
[downloads_img]: https://img.shields.io/npm/dm/react-fast-compare.svg
[maintenance_img]: https://img.shields.io/badge/maintenance-active-flatgreen.svg