A simple Object and Array extension that allows for easy grouping.
npm install group_by
require('group_by')
var x = [1,2,3,4]
var grouping_key_generator = function(o) {
if(o%2==0)
return 'even';
return 'odd'
}
var groups = x.group_by(grouping_key_generator);
console.log(groups);
{ __keys : [ 'odd', 'even' ] , odd : [ 1, 3 ] , even : [ 2, 4 ] }