29 lines
661 B
Markdown
29 lines
661 B
Markdown
---
|
|
title: Transform object
|
|
tags: object
|
|
cover: fishermen
|
|
firstSeen: 2018-01-12T13:55:49+02:00
|
|
lastUpdated: 2020-10-22T20:24:44+03:00
|
|
---
|
|
|
|
Applies a function against an accumulator and each key in the object (from left to right).
|
|
|
|
- Use `Object.keys()` to iterate over each key in the object.
|
|
- Use `Array.prototype.reduce()` to apply the specified function against the given accumulator.
|
|
|
|
```js
|
|
const transform = (obj, fn, acc) =>
|
|
Object.keys(obj).reduce((a, k) => fn(a, obj[k], k, obj), acc);
|
|
```
|
|
|
|
```js
|
|
transform(
|
|
{ a: 1, b: 2, c: 1 },
|
|
(r, v, k) => {
|
|
(r[v] || (r[v] = [])).push(k);
|
|
return r;
|
|
},
|
|
{}
|
|
); // { '1': ['a', 'c'], '2': ['b'] }
|
|
```
|