44 lines
1.4 KiB
Markdown
44 lines
1.4 KiB
Markdown
---
|
|
title: Check object equality
|
|
type: snippet
|
|
tags: [object,array,type,recursion]
|
|
cover: beach-pineapple
|
|
dateModified: 2021-10-13T19:29:39+02:00
|
|
---
|
|
|
|
Performs a deep comparison between two values to determine if they are equivalent.
|
|
|
|
- Check if the two values are identical.
|
|
- Check if both values are `Date` objects with the same time, using `Date.prototype.getTime()`.
|
|
- Check if both values are non-object values with an equivalent value (strict comparison).
|
|
- Check if only one value is `null` or `undefined` or if their prototypes differ.
|
|
- If none of the above conditions are met, use `Object.keys()` to check if both values have the same number of keys.
|
|
- Use `Array.prototype.every()` to check if every key in `a` exists in `b` and if they are equivalent by calling `equals()` recursively.
|
|
|
|
```js
|
|
const equals = (a, b) => {
|
|
if (a === b) return true;
|
|
|
|
if (a instanceof Date && b instanceof Date)
|
|
return a.getTime() === b.getTime();
|
|
|
|
if (!a || !b || (typeof a !== 'object' && typeof b !== 'object'))
|
|
return a === b;
|
|
|
|
if (a.prototype !== b.prototype) return false;
|
|
|
|
const keys = Object.keys(a);
|
|
if (keys.length !== Object.keys(b).length) return false;
|
|
|
|
return keys.every(k => equals(a[k], b[k]));
|
|
};
|
|
```
|
|
|
|
```js
|
|
equals(
|
|
{ a: [2, { e: 3 }], b: [4], c: 'foo' },
|
|
{ a: [2, { e: 3 }], b: [4], c: 'foo' }
|
|
); // true
|
|
equals([1, 2, 3], { 0: 1, 1: 2, 2: 3 }); // true
|
|
```
|