Javascript ES6 将对象数组拆分为两个不同的对象子数组

Question

I have an array of objects or json called obj.credits: [] that contains about 50 credit objects. Each credit object has a cast_id field that is either null or not null

I want to completely filter all objects having null cast_id into a subarray obj.credits.crew: [] and all objects having not null cast_id into another subarray obj.credits.cast: [] .

After that obj.credits should only contain keys cast and crew .

The following is not working. it creates subarrays but does not delete the original array objects

 obj.credits.cast = obj.credits.filter(credit => credit.cast_id != null)
 obj.credits.crew = obj.credits.filter(credit => credit.cast_id == null)

Answer 1

The problem you are having is the fact you are acting like an Array is an Object. You are just adding properties to your array. If you want it to be an object, you need to rethink how you are doing this.

So you want a final output of an object with two properties that contain arrays, so replace obj.credits with an object.

obj.credits = obj.credits.reduce((acc, credit) => {
  if (credit.cast_id != null) acc.cast.push(credit);
  else acc.crew.push(credit);
  return acc;
}, { cast: [], crew: [] });

Answer 2

obj.credits is an array. You can't add cast and crew properties into this. So you can create 2 separate sub-arrays -

let cast = obj.credits.filter(credit => credit.cast_id != null)
let crew = obj.credits.filter(credit => credit.cast_id == null)

Then clear the obj.credits array and initialize it as an object. Then add these sub-arrays as properties.

obj.credits = {};
obj.credits = {cast, crew};

Answer 3

This way, you do not have to traverse the array twice just to separate cast from crew.

const cast = [];
const crew = [];
for (const item of obj.credits){
  if (!item) continue;
  if (item.cast_id) cast.push(item);
  else crew.push(item);
}
obj.credits.cast = cast;
obj.credits.crew = crew;

Answer 4

Not a very easy question to understand. The long way around this (that will work) is to initialise two new arrays (credits.crew and credits.cast), loop through your main array checking the key if it is null or not and then adding that record to one of the new arrays. This assumes you have the write methods on the object to get its value.

Answer 5

To remove all iterable elements from a list, set its length to zero. Example below.

 let obj = {} obj.credits = [ {cast_id: 1}, {cast_id: 2}, {cast_id: null} ] obj.credits.cast = obj.credits.filter(credit => credit.cast_id != null) obj.credits.crew = obj.credits.filter(credit => credit.cast_id == null) // remove all elements from `credits` property of `obj` obj.credits.length = 0 document.write(JSON.stringify(obj), '<br>') document.write(JSON.stringify(obj.credits), '<br>') document.write(JSON.stringify(obj.credits.cast), '<br>') document.write(JSON.stringify(obj.credits.crew))