groubbykey js
function groupByKey(array, key) {
return array
.reduce((hash, obj) => {
if(obj[key] === undefined) return hash;
return Object.assign(hash, { [obj[key]]:( hash[obj[key]] || [] ).concat(obj)})
}, {})
}
var cars = [{'make':'audi','model':'r8','year':'2012'},{'make':'audi','model':'rs5','year':'2013'},{'make':'ford','model':'mustang','year':'2012'},{'make':'ford','model':'fusion','year':'2015'},{'make':'kia','model':'optima','year':'2012'}];
console.log(groupByKey(cars, 'make'))
Comfortable Cottonmouth