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

You can also make use of array#forEach() method like this:

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' }];

let newcars = {}

cars.forEach(car => {
  newcars[car.make] ? // check if that array exists or not in newcars object
    newcars[car.make].push({model: car.model, year: car.year})  // just push
   : (newcars[car.make] = [], newcars[car.make].push({model: car.model, year: car.year})) // create a new array and push
})

console.log(newcars);