Delete objects from the array of object which reference id did not matches with any other object id-CodePudding

I want to delete those objectσ which refId id that dont match with any id of array of object, if refId is null dont delete it

[
  {id: 1 , refId:null, name:'jhon'},
  {id: 2 , refId:null, name:'sam'}, 
  {id: 3 , refId:1, name:'fam'},
  {id: 4 , refId:2, name:'jam'}, 
  {id: 5 , refId:16, name:'ram'}, 
  {id: 6 , refId:15, name:'nam'}
]

result: should b:

[
  {id: 1 , refId:null, name:'jhon'}, 
  {id: 2 , refId:null, name:'sam'}, 
  {id: 3 , refId:1, name:'fam'},
  {id: 4 , refId:2, name:'jam'},
]

CodePudding user response：

Please try once with following code:

const arr1 = [
  { id: 1, refId: null, name: "jhon" },
  { id: 2, refId: null, name: "sam" },
  { id: 3, refId: 1, name: "fam" },
  { id: 4, refId: 2, name: "jam" },
  { id: 5, refId: 16, name: "ram" },
  { id: 6, refId: 15, name: "nam" },
];

console.log(
  arr1.filter((obj) => {
    return obj.refId === null || arr1.some((o) => o.id === obj.refId);
  })
);

CodePudding user response：

What you have here is a tree structure, if the tree is small using a filter or some is fine, but if the tree is large you should try doing it with a mapping(dictionary).

let nodes = [
  {id: 1 , refId:null, name:'jhon'},
  {id: 2 , refId:null, name:'sam'}, 
  {id: 3 , refId:1, name:'fam'},
  {id: 4 , refId:2, name:'jam'}, 
  {id: 5 , refId:16, name:'ram'}, 
  {id: 6 , refId:15, name:'nam'}
]

let dictionary = nodes.reduce((dic, node) => { dic[node.id] = true; return  dic; }, { [null]: true });
let result = nodes.filter((node) => dictionary[node.refId]);

console.log(result);