recursing filter array js - Javascript

SergeyGrenaderov
April 9, 2023
249 views
2 votes
4 Answers

i have array:

[
 {id: 1, name: 'Parent1'},
 {id: 2, name: 'Child1', parent: {id: 1, name: 'Parent1'}},
 {id: 3, name: 'Child2', parent: {id: 1, name: 'Parent1'}},
 {id: 4, name: 'GrandChild1', parent: {id: 3, name: 'Child2'}},
 {id: 5, name: 'GrandChild2', parent: {id: 3, name: 'Child2'}}
]

I need to write a function with an id argument that will return an array that does not include the element with id and all of its children and children of childrens. Help pls

I tries write recursing function but fallen

Answers

function filterByIdAndChildren(id, arr) {
  const filteredArray = [];

  function filterItems(inputId, array) {
    for (const item of array) {
      if (item.id !== inputId) {
        if (item.parent && item.parent.id === inputId) {
          filterItems(item.id, array);
        } else {
          filteredArray.push(item);
          if (item.parent) {
            filterItems(inputId, [item.parent]);
          }
        }
      }
    }
  }

  filterItems(id, arr);
  return filteredArray;
}

it should be work!

const validArr = item => typeof item.age === 'number' && item.age > 17;

const thisWontWork = arr => {
  return arr.filter(item => {
    if (item.id) {
      // here is the recursive call
      return thisWontWork(item.id).length > 0 && validArr(item);
    } else return validArr(item);
  });
};
    
log(thisWontWork(name));

You could store the unwanted parents for later filtering out.

This approach works for unsorted items.

const
    filter = (array, id) => {
        const
            parents = Object.fromEntries(array.map(({ id, parent = {} }) => [id, parent.id])),
            isParent = pid => id === parents[pid] || pid in parents && isParent(parents[pid]);
        return array.filter(o => o.id !== id && !isParent(o.id));
    },
    data = [{ id: 1, name: 'Parent1' }, { id: 2, name: 'Child1', parent: { id: 1, name: 'Parent1' } }, { id: 3, name: 'Child2', parent: { id: 1, name: 'Parent1' } }, { id: 4, name: 'GrandChild1', parent: { id: 3, name: 'Child2' } }, { id: 5, name: 'GrandChild2', parent: { id: 3, name: 'Child2' } }];

console.log(filter(data, 1));
console.log(filter(data, 2));
console.log(filter(data, 3));
console.log(filter(data, 4));
console.log(filter(data, 5));

.as-console-wrapper { max-height: 100% !important; top: 0; }

That is how I would approach the problem

let values = [
 {id: 1, name: 'Parent1'},
 {id: 2, name: 'Child1', parent: {id: 1, name: 'Parent1'}},
 {id: 3, name: 'Child2', parent: {id: 1, name: 'Parent1'}},
 {id: 4, name: 'GrandChild1', parent: {id: 3, name: 'Child2'}},
 {id: 5, name: 'GrandChild2', parent: {id: 3, name: 'Child2'}},
 {id: 6, name: 'GreatGrandChild', parent: {id: 5, name: 'GrandChild2'}},
 {id: 11, name: 'Parent2'},
 {id: 12, name: 'Child1ToParent2', parent: {id: 11, name: 'Parent2'}},
 {id: 13, name: 'Child2ToParent2', parent: {id: 11, name: 'Parent2'}},
 {id: 14, name: 'GrandChild1ToParent2', parent: {id: 13, name: 'Child2ToParent2'}},
 {id: 15, name: 'GrandChild2ToParent2', parent: {id: 13, name: 'Child2ToParent2'}},
 {id: 16, name: 'GreatGrandChildToParent2', parent: {id: 15, name: 'GrandChild2ToParent2'}},
]

function isDescendant(idRoot, node) {
    // If no parent, it is one of the roots of the family tree so we return false
    if (!node.parent) {
        return false;
    }

    // Else, finds the parent in the list.
    const parent = values.find(value => value.id === node.parent.id);

    //Checks if it is the right parent.
    if (idRoot === parent.id) {
        return true;
    }

    // Is a great children -> continue recursively
    return isDescendant(idRoot, parent);
}

let filteredValues = values.filter(x => isDescendant(1, x))
console.log(filteredValues);

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recursing filter array js – Javascript

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