Angular 比较数组并更新其中一个

Question

I have this two sets of array, I need to compare them and if the object from 2th array found on 1st array, I need to update the status on 1st array to true. On angular how to massage the data, thanks!

Below are sample of array,

arr1 = [
  {id: 1, status: false},
  {id: 2, status: false},
  {id: 3, status: false}
];

arr2 = [
  {id: 4},
  {id: 5},
  {id: 2}
];

Answer 1

Even though you have not provided any (faulty) code from yourself, I understand that it sometimes can be difficult to even begin with such a thing.

In this case, you should find a beginning point. You can use the source array ( arr1 ) as starting point, or arr2 . If arr2 is tiny, it's quicker to use this as starting point. The bigger arr2 gets, the more you might want to start with arr1 , because that solution is more readable (subjective).

With arr2 as starting point, you can use the forEach method, in combination with find :

arr2.forEach((item) => {
  const target = arr1.find(({ id }) => item.id === id);

  if (target) {
    target.status = true;
  }
});

With the arr1 as starting point, you can use the map method. This will make a new array in place, which is usually a good thing to do, considering angular's change detection system:

arr1 = arr1.map((item) => ({
  ...item,
  status: arr2.some(({ id }) => item.id === id)
});

This will also create a new object reference. Depending on your data set, performance might be an issue, but this will only be noticable if you are processing +10.000 objects (depending on the complexity of your objects).

If you do not want a status: true be overwritten to false on arr1 , you need to add an extra condition:

arr1 = arr1.map((item) => ({
  ...item,
  status: item.status || arr2.some(({ id }) => item.id === id)
});