How to recursively transform an array of nested objects into array of flat objects?

Question

I have the following array of deeply nested objects:

const data = [
    {
      name: "foo",
      children:[
        {
          count: 1,
          name: "A"
        },
        { 
          count: 2,
          name: "B"
        }
      ]
    },
    {
      name: "bar",
      children: [
        {
          count: 3,
          name: "C",
          children: [
            {
              count: 4,
              name: "D"
            }
          ]
        }
      ]
    }
  ]

The way I'd like to transform this would be such as:

const expectedStructure = [
    {
      count: 1,
      name: "A",
      label: "foo = A"
    },
    {
      count: 2,
      name: "B",
      label: "foo = B"
    },
    {
      count: 3,
      name: "C",
      label: "bar = C"
    },
    {
      count: 4,
      name: "D",
      label: "bar = D"
    }
  ]

I created recursive function that transforms nested array into array of flat objects.

Here's my code:

function getChildren(array, result=[]) {
    array.forEach(({children, ...rest}) => {
        result.push(rest);
        if(children) {
            getChildren(children, result);
        }
    });
    return result;
}

And here's output I get:

[ { name: 'foo' },
  { count: 1, name: 'A' },
  { count: 2, name: 'B' },
  { name: 'bar' },
  { count: 3, name: 'C' },
  { count: 4, name: 'D' } ]

The problem is that I need to add label field to every object in my output array, and I can't find a solution without iterating multiple times through the final array to make desired transformation. How to properly insert label field without hugely augmenting complexity of the function?

Answer 1

Check each iteration whether the current item is a "parent" item, and reassign label if it is.

const data = [{name:"foo",children:[{count:1,name:"A"},{count:2,name:"B"}]},{name:"bar",children:[{count:3,name:"C",children:[{count:4,name:"D"}]}]}];

function getChildren(array, result = [], label = "") {
  array.forEach(({ children, name, count }) => {
    if (!label || name[1]) {
      label = `${name} = `;
    }
    if (count) {
      result.push({ count, name, label: label + name });
    }
    if (children) {
      getChildren(children, result, label);
    }
  });
  return result;
}

const res = getChildren(data);

console.log(res);