将一个数组的对象按键合并为一个object

Question

I am trying to merge objects of an array into one if they have the same key.

Having this array:

let data = [
  { id: "1", cars: 5 }, 
  { id: "1", pasta: 2 },
  { id: "2", cars: 0 }, 
  { id: "2", pasta: 0 },
];

I would like to achieve this:

let data = [
  { id: "1", cars: 5, pasta: 2 },
  { id: "2", cars: 0, pasta: 0 },
];

I am looking for any solutions, but preferable ES6.

Answer 1

Here's a solution that combines the Array reduce method and the Object values method. One benefit of this approach is that it is O(n) time complexity, which would only really matter if you had a ton of data, but still potentially more efficient than the solutions that include loops inside loops.

 let data = [ { id: "1", cars: 5 }, { id: "1", pasta: 2 }, { id: "2", cars: 0 }, { id: "2", pasta: 0 }, ]; const combined = Object.values(data.reduce((acc, el) => { acc[el.id] = {...acc[el.id], ...el }; return acc; }, {})); console.log(combined);

Answer 2

Using Array.prototype.reduce() :

 let data = [ { id: "1", cars: 5 }, { id: "1", pasta: 2 }, { id: "2", cars: 0 }, { id: "2", pasta: 0 }, ] const result = data.reduce((items, item) => { const existingItem = items.find(({ id }) => id === item.id) if (existingItem) Object.assign(existingItem, item) else items.push({...item }) return items }, []) console.log(result) // Original array is left intact: console.log(data)