Update and rename sqaure_it.md to mapObject.md

This commit is contained in:
Angelos Chalaris
2017-12-18 12:11:58 +02:00
committed by GitHub
parent c3de880e41
commit 42bff6deb6
2 changed files with 14 additions and 11 deletions

14
snippets/mapObject.md Normal file
View File

@ -0,0 +1,14 @@
### mapObject
Maps the values of an array to an object using a function, where the key-value pairs consist of the original value as the key and the mapped value.
Use an anonymous inner function scope to declare an undefined memory space, using closures to store a return value. Use a new `Array` to stor the array with a map of the function over its data set and a comma operator to return a second step, without needing to move from one context to another (due to closures and order of operations).
```js
const mapObject = (arr, fn) =>
(a => (a = [arr, arr.map(fn)], a[0].reduce( (acc,val,ind) => (acc[val] = a[1][ind], acc), {}) )) ( );
/*
const squareIt = arr => mapObject(arr, a => a*a)
squareIt([1,2,3]) // { 1: 1, 2: 4, 3: 9 }
*/
```