我想根据它们的 id 对两个数组的对象进行联合

Question

Let suppose I have two array

let array1 = [{id: 1,name: "a"},{id: 2,name: "b"}]
let array2 = [{id: 1,name: 'c'},{id: 3,name: 'd'}]

and I want the resulting array to be like so

let result = [{id: 1,name: 'c'},{id: 2,name: 'b'},{id: 3,name: 'd'}]

So if the second array has an object and the first array also has an object with the same id then replace the first object with the second array object. Currently, I have try below code but it checks for each value to match and I want to match on id based only

const uniqueArray = this.servicesdata.filter((item, index) => {
        const _item = JSON.stringify(item);
        return (
          index ===
          this.servicesdata.findIndex(obj => {
            return JSON.stringify(obj) === _item;
          })
        );
      });
      console.log(uniqueArray);

Answer 1

Here's a O(NlogN) approach.

let array1 = [{id: 1,name: "a"},{id: 2,name: "b"}] // Let's say its size is N1
let array2 = [{id: 1,name: 'c'},{id: 3,name: 'd'}] // Let's say its size is N2
let duplicate  = new Set() // A set to check for duplicate elements
let result = array2
array2.forEach((item)=>{ // O(N2logN2)
    duplicate.add(item.id);
})
array1.forEach((item)=>{ // O(N1logN2)
    // If `duplicate` does NOT have `item.id`, that means it's unique in array1, so add it to result
    // Otherwise, skip it because for duplicates, we want value from array2
    if(!duplicate.has(item.id))
        result.push(item);
})
// Overall complexity of approach - O(N2logN2) + O(N1logN2) ==> O(NlogN)
console.log(result);

Output:

[ { id: 1, name: 'c' },
  { id: 3, name: 'd' },
  { id: 2, name: 'b' } ]

Answer 2

With lodash you can use unionBy :

 let array1 = [{id: 1,name: "a"},{id: 2,name: "b"}] let array2 = [{id: 1,name: 'c'},{id: 3,name: 'd'}] console.log(_.unionBy(array2, array1, 'id'))

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