I'm really not sure how to word this issue but I will try my best.

I have a nested array:

const items = [
  {
    id: 1,
    name: "Test name",
    children: [
      {
        id: 5,
        name: "Test name 5",
        children: [
          {
            id: 6,
            name: "Test name 6",
            children: [],
          },
        ],
      },
    ],
  },
  {
    id: 8,
    name: "Test name 8",
    children: [
      {
        id: 9,
        name: "Test name 9",
        children: [],
      },
    ],
  },
];

and I have an array of indexes where to target and update

const keys = [0,0,0]

The array of indexes should target Test name 6

How can I update Test name 6 to something else?

p.s. items and keys are dynamic. there might be dozens of nested items or dozens of indexes in keys

CodePudding user response：

You could reduce the indices and check the children property.

After getting the final object, just assign the value to the wanted property.

const
    getItem = (children, keys) => keys.reduce(
        ({ children = [] }, i) => children[i],
        { children }
    ),
    items = [{ id: 1, name: "Test name", children: [{ id: 5, name: "Test name 5", children: [{ id: 6, name: "Test name 6", children: [] }] }] }, { id: 8, name: "Test name 8", children: [{ id: 9, name: "Test name 9", children: [] }] }],
    keys = [0, 0, 0];
    
console.log(getItem(items, keys));

CodePudding user response：

To update your nested array first you will first need to change it to a mutable variable, i.e. from a const to a let or var.

From there you can update the value with something like:

// Copy pasted data from your post
let items = [
  {
    id: 1,
    name: "Test name",
    children: [
      {
        id: 5,
        name: "Test name 5",
        children: [
          {
            id: 6,
            name: "Test name 6",
            children: [],
          },
        ],
      },
    ],
  },
  {
    id: 8,
    name: "Test name 8",
    children: [
      {
        id: 9,
        name: "Test name 9",
        children: [],
      },
    ],
  },
];

const keys = [0,0,0]

// <----------------- CODE BELOW ---------------->

// var to store item each time you dive deeper into the nested array
// initalize with the first item
let item = items[keys[0]].children;

// loop through each key
for(let i = 1; i < keys.length; i  ){
  // if we are at the last key, set item equal to the item object
  if(i == keys.length-1){
    item = item[keys[i]];
  }
  // otherwise, set item equal to the item's children
  else{
    item = item[keys[i]].children
  }
}

// once item has been reached - all keys have been looped through - data can be minupulated
item.name = "new value"
// "Test name 6" has been updated to "new value"

emphasized text

CodePudding user response：

In this scenario, I usually use a Map referencing the items within the nested arrays. For example:

const items = [
  {
    id: 1,
    name: "Test name",
    children: [
      {
        id: 5,
        name: "Test name 5",
        children: [
          {
            id: 6,
            name: "Test name 6",
            children: [],
          },
        ],
      },
    ],
  },
  {
    id: 8,
    name: "Test name 8",
    children: [
      {
        id: 9,
        name: "Test name 9",
        children: [],
      },
    ],
  },
];

const createItemsMap = items => {
  const m = new Map();
  
  (function _collect(items) {
    for (const item of items) {
      m.set(item.id, item);
      if (item.children) {
        _collect(item.children);
      }
    }
  })(items);
  
  return m;
}

const itemsMap = createItemsMap(items);

// modify item #6
itemsMap.get(6).name = "Modified name 6";

console.log("itemsMap.get(1) === items[0] is", itemsMap.get(1) === items[0]);
console.log(items);

With that map, modifying the items is simply a matter of doing this :

const item = itemsMap.get(id);

item.name = "Foo";

To get the keys of that map :

const keys = Array.from(itemsMap.keys());

Note: If items is modified directly (i.e. items are added or removed), then itemsMap needs to be re-generated. In any other case, both items and itemsMap reference to the same data.