From 91f393207df999ed0ef1cf715f08426d570bd426 Mon Sep 17 00:00:00 2001 From: Angelos Chalaris Date: Thu, 14 Dec 2017 10:45:09 +0200 Subject: [PATCH] Update group-by Shortened code. It now also follows the styleguide more precisely. Improved description. --- snippets/group-by | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/snippets/group-by b/snippets/group-by index 53383db3a..e6df1a2a7 100644 --- a/snippets/group-by +++ b/snippets/group-by @@ -1,16 +1,14 @@ ### Group by -Passing an array of values, a function or a property name thats going to be run against each value in the array, -returns an object where the keys are the mapped results and the values is an array of the original values that generated the same results. +Use `Array.map()` to map the values of an array to a function or property name. +Use `Array.reduce()` to create an object, where the keys are produced from the mapped results. ```js -const groupBy = (values, fn) => { - return (typeof fn === 'function' ? values.map(fn) : values.map((val) => val[fn])) +const groupBy = (arr, func) => + (typeof func === 'function' ? arr.map(func) : arr.map(val => val[func])) .reduce((acc, val, i) => { - acc[val] = acc[val] === undefined ? [values[i]] : acc[val].concat(values[i]); - return acc; + acc[val] = acc[val] === undefined ? [arr[i]] : acc[val].concat(arr[i]); return acc; }, {}); -} // groupBy([6.1, 4.2, 6.3], Math.floor) -> {4: [4.2], 6: [6.1, 6.3]} // groupBy(['one', 'two', 'three'], 'length') -> {3: ['one', 'two'], 5: ['three']} ```