moroshko / shallow-equal Goto Github PK

Minimalistic shallow equality check for arrays/objects

License: MIT License

TypeScript 100.00%

shallow equal equals equality equality-check object array objects arrays

shallow-equal's Introduction

Description

If you know you have two arrays or two objects in hand, and you want to know if they are shallowly equal or not, this library is for you.

Features

Super light
No dependencies
Thoroughly tested

Installation

npm install shallow-equal --save

yarn add shallow-equal

Usage

import { shallowEqualArrays } from "shallow-equal";

shallowEqualArrays([1, 2, 3], [1, 2, 3]); // => true
shallowEqualArrays([{ a: 5 }], [{ a: 5 }]); // => false

import { shallowEqualObjects } from "shallow-equal";

shallowEqualObjects({ a: 5, b: "abc" }, { a: 5, b: "abc" }); // => true
shallowEqualObjects({ a: 5, b: {} }, { a: 5, b: {} }); // => false

You can also use the generic form, shallowEqual. But note that it does runtime type checking in order to decide whether it's comparing arrays or objects, so the convenience comes with a runtime penalty.

import { shallowEqual } from "shallow-equal";

shallowEqual([1, 2, 3], [1, 2, 3]); // => true
shallowEqual({ a: 5, b: {} }, { a: 5, b: {} }); // => false

shallow-equal's People

Contributors

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juliangruber nobabel koblas ndelangen eps1lon amokrunner fivecar

shallow-equal's Issues

Update shallow equal objects

I would to request to update the shallow equal for objects with the following one

https://github.com/reactjs/react-redux/blob/master/src/utils/shallowEqual.js

React-redux guys update it recently in order to use the shallowEqual they use in fbjs. This piece of code also manages number cases

ESM support

Hey,

we needed shallow equal function here and it turned out neither fbjs/lib/shallowEqual nor this package support ESM. The problem here is that we configured rollup to only take ESM modules and we actively avoid any cjs modules for both reasons, moving ecosystem forward and having only treeshakable dependencies.

Can we please add an ESM entry point to this module?

TS support

That would be cool to ship TS defs for this package ;)

version 3 module will not load due to the wrong file extension in package.json

When using version 3 I'm getting the error Could not load './dist/index.modern.js' from module 'shallow-equal' found in package.json#module

    5 |   "main": "dist/index.js",
  > 6 |   "module": "dist/index.modern.js",
  >   |             ^^^^^^^^^^^^^^^^^^^^^^ './dist/index.modern.js' does not exist, did you mean './dist/index.modern.mjs'?'
    7 |   "source": "src/index.ts",
    8 |   "types": "dist/index.d.ts",

The file is actually index.modern.mjs in the dist folder.

Inheritence is not handled well

The object implementation essentially checks whether:

a and b have the same number of own properties, and
all of the own properties in a equal any kind of properties in b, including inherited ones.

Because the implementation does not check whether the property in b is its own or not, it can be fooled. Try adding this test case:

  {
    should: 'return false for the false king',
    objA: {
      crownWearer: true
    },
    objB: (function createFalseKing() {
      var spider = {
        crownWearer: true
      }

      function FalseKing() {
        this.objective = 'world domination';
      }

      FalseKing.prototype = spider;

      return new FalseKing();
    })(),
    result: false
  }

If I pass one parameter as a string in shallowEqualArrays('abc', [1,2,3]) then it will give me exception. It is because in this method it is finding length of first parameter and for string it will fail

Array comparison allows primitives to pass

If you pass two equal primitive to the array comparison method it'll return true. Perhaps add this at the top:

if (!Array.isArray(arrA) || !Array.isArray(arrB)) {
  return false
}

Undefined properties not handled correctly

The following code returns true, when the two objects are clearly not equal.

 shallowEqualObjects({ a: undefined }, { b: 1 }))