Merging an array of objects without overwriting

Question

I am currently with some JSON, which has to be structured in a tree-like hierarchy. The depth of the hierarchy varies a lot, and is therefor unknown.

As it is right now, I have achieved to get an array of objects. Example is below.

[
    {
      "name": "level1",
      "collapsed": true,
      "children": [
        {
          "name": "Level 1 item here",
          "id": 360082134191
        }
      ]
    },
    {
      "name": "level1",
      "collapsed": true,
      "children": [
        {
          "name": "level2",
          "collapsed": true,
          "children": [
            {
              "name": "Level 2 item here",
              "id": 360082134751
            }
          ]
        }
      ]
    },
    {
      "name": "level1",
      "collapsed": true,
      "children": [
        {
          "name": "Another level 1 item",
          "id": 360082262772
        }
      ]
    }
  ]

What I want to achieve is these objects to be merged, without overwriting or replacing anything. Listed below is an example of how I want the data formatted:

[
  {
    "name": "level1",
    "collapsed": true,
    "children": [
      {
        "name": "level2",
        "collapsed": true,
        "children": [
          {
            "name": "Level 2 item here",
            "id": 360082134751
          }
        ]
      },
      {
        "name": "Level 1 item here",
        "id": 360082134191
      },
      {
        "name": "Another level 1 item",
        "id": 360082262772
      }
    ]
  }
]

How would I achieve this with JavaScript? No libraries is preferred, ES6 can be used though.

Edit: It is important that the output is an array, since items without children can appear at the root.

Answer 1

I am assuming you need a little help on working with the data. There could be multiple ways to achieve this, here is how would I do.

// data => supplied data
const result = data.reduce ((acc, item) => {
  // if acc array already contains an object with same name,
  // as current element [item], merfe the children
  let existingItem;

  // Using a for loop here to create a reference to the
  // existing item, so it'd update this item when childrens
  // will be merged.
  for (let index = 0; index < acc.length; index ++) {
    if (acc[index].name === item.name) {
      existingItem = acc[index];
      break;
    }
  }
  // if existingItem exists, merge children of
  // existing item and current item.
  // else push it into the accumulator
  if (existingItem) {
    existingItem.children = existingItem.children.concat(item.children);
  } else {
    acc.push (item);
  }
  return acc;
}, []);

Answer 2

I'm assuming you want to group based on the name property in the level 1 object. You could do a simple reduce and Object.values like this:

 const input = [{"name":"level1","collapsed":true,"children":[{"name":"Level 1 item here","id":360082134191}]},{"name":"level1","collapsed":true,"children":[{"name":"level2","collapsed":true,"children":[{"name":"Level 2 item here","id":360082134751}]}]},{"name":"level1","collapsed":true,"children":[{"name":"Another level 1 item","id":360082262772}]}] const merged = input.reduce((r,{name, collapsed, children}) =>{ r[name] = r[name] || {name, collapsed, children:[]}; r[name]["children"].push(...children) return r; }, {}) const final = Object.values(merged); console.log(final) 

You could do the whole thing in one line:

 const input = [{"name":"level1","collapsed":true,"children":[{"name":"Level 1 item here","id":360082134191}]},{"name":"level1","collapsed":true,"children":[{"name":"level2","collapsed":true,"children":[{"name":"Level 2 item here","id":360082134751}]}]},{"name":"level1","collapsed":true,"children":[{"name":"Another level 1 item","id":360082262772}]}] const output = Object.values(input.reduce((r,{name,collapsed,children}) => ( (r[name] = r[name] || {name,collapsed,children: []})["children"].push(...children), r), {})) console.log(output)