I have a nested array of objects like this:

let data = [
  {
      id: 1,
      title: "Abc",
      children: [
          {
              id: 2,
              title: "Type 2",
              children: [
                  {
                      id: 23,
                      title: "Number 3",
                      children:[] /* This key needs to be deleted */
                  }
              ]
          },
      ]
  },
  {
      id: 167,
      title: "Cde",
      children:[] /* This key needs to be deleted */
  }
] 

All I want is to recursively find leaves with no children (currently an empty array) and remove the children property from them.

Here's my code:

normalizeData(data, arr = []) {
    return data.map((x) => {
        if (Array.isArray(x))
            return this.normalizeData(x, arr)
        return {
            ...x,
            title: x.name,
            children: x.children.length ? [...x.children] : null
        }
    })
}

I have a nested array of objects like this:

let data = [
  {
      id: 1,
      title: "Abc",
      children: [
          {
              id: 2,
              title: "Type 2",
              children: [
                  {
                      id: 23,
                      title: "Number 3",
                      children:[] /* This key needs to be deleted */
                  }
              ]
          },
      ]
  },
  {
      id: 167,
      title: "Cde",
      children:[] /* This key needs to be deleted */
  }
] 

All I want is to recursively find leaves with no children (currently an empty array) and remove the children property from them.

Here's my code:

normalizeData(data, arr = []) {
    return data.map((x) => {
        if (Array.isArray(x))
            return this.normalizeData(x, arr)
        return {
            ...x,
            title: x.name,
            children: x.children.length ? [...x.children] : null
        }
    })
}

• javascript
• dictionary
• filter
• nested-object

• 1 Your efforts till now ? – Code Maniac Commented Jan 26, 2019 at 14:10
• 1 added code, please take a look – Amir Shahbabaie Commented Jan 26, 2019 at 14:13

4 Answers 4

You need to use recursion for that:

let data = [{
    id: 1,
    title: "Abc",
    children: [{
      id: 2,
      title: "Type 2",
      children: [{
        id: 23,
        title: "Number 3",
        children: [] /* This key needs to be deleted */
      }]
    }]
  },
  {
    id: 167,
    title: "Cde",
    children: [] /* This key needs to be deleted */
  }
]

function traverse(obj) {
  for (const k in obj) {
    if (typeof obj[k] == 'object' && obj[k] !== null) {
      if (k === 'children' && !obj[k].length) {
        delete obj[k]
      } else {
        traverse(obj[k])              
      }
    }
  }
}

traverse(data)
console.log(data)

Nik's answer is fine (though I don't see the point of accessing the children key like that), but here's a shorter alternative if it can help:

let data = [
  {id: 1, title: "Abc", children: [
    {id: 2, title: "Type 2", children: [
      {id: 23, title: "Number 3", children: []}
    ]}
  ]},
  {id: 167, title: "Cde", children: []}
];

data.forEach(deleteEmptyChildren = o => 
  o.children.length ? o.children.forEach(deleteEmptyChildren) : delete o.children);

console.log(data);

If children is not always there, you can change the main part of the code to:

data.forEach(deleteEmptyChildren = o => 
  o.children && o.children.length 
    ? o.children.forEach(deleteEmptyChildren) 
    : delete o.children);

Simple recursion with forEach is all that is needed.

let data = [{
    id: 1,
    title: "Abc",
    children: [{
      id: 2,
      title: "Type 2",
      children: [{
        id: 23,
        title: "Number 3",
        children: [] /* This key needs to be deleted */
      }]
    }, ]
  },
  {
    id: 167,
    title: "Cde",
    children: [] /* This key needs to be deleted */
  }
]

const cleanUp = data =>
  data.forEach(n =>
    n.children.length
      ? cleanUp(n.children)
      : (delete n.children))
      
      
cleanUp(data)
console.log(data)

This assumes children is there. If it could be missing than just needs a minor change to the check so it does not error out on the length check. n.children && n.children.length

You can do it like this using recursion.

So here the basic idea is in removeEmptyChild function we check if the children length is non zero or not. so if it is we loop through each element in children array and pass them function again as parameter, if the children length is zero we delete the children key.

let data=[{id:1,title:"Abc",children:[{id:2,title:"Type2",children:[{id:23,title:"Number3",children:[]}]},]},{id:167,title:"Cde",children:[]},{id:1}]

function removeEmptyChild(input){
  if( input.children && input.children.length ){
    input.children.forEach(e => removeEmptyChild(e) )
  } else {
    delete input.children
  }
  return input
}

data.forEach(e=> removeEmptyChild(e))

console.log(data)