Group By Property
JAVASCRIPT
Hard
+40 XP
Problem Description
Write a function `groupBy(arr, key)` that groups an array of objects by a given key.
Example:
groupBy([{type:'a',val:1},{type:'b',val:2},{type:'a',val:3}], 'type')
→ { a: [{type:'a',val:1},{type:'a',val:3}], b: [{type:'b',val:2}] }
Example:
groupBy([{type:'a',val:1},{type:'b',val:2},{type:'a',val:3}], 'type')
→ { a: [{type:'a',val:1},{type:'a',val:3}], b: [{type:'b',val:2}] }
Your Solution