How to group an array of objects by key

Question

Does anyone know of a (lodash if possible too) way to group an array of objects by an object key then create a new array of objects based on the grouping? For example, I hav

Answer 1

Here is your very own groupBy function which is a generalization of the code from: https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore

function groupBy(xs, f) {
  return xs.reduce((r, v, i, a, k = f(v)) => ((r[k] || (r[k] = [])).push(v), r), {});
}

const 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' }];

const result = groupBy(cars, (c) => c.make);
console.log(result);