Recursively create a parent and child string for every child and it's child-CodePudding

I'm attempting to create an array of objects as the final output which includes the parent name and it's children. The id would be the last child in the name

Sample output I'm trying to achieve :

[
{id:1,name:"1"},
{id:2,name:"1-2"},
{id:3,name:"1-2-3"},
{id:4,name:"1-2-4"}
]

Code:

let item = {
  id: 1,
  name: "1",
  children: [{
    id: 2,
    name: "2",
    children: [{
        id: 3,
        name: "3",
        children: []
      },
      {
        id: 4,
        name: "4",
        children: []
      }
    ]
  }]
}


const createList = (item) => {

  let name = item.children.map(e => {
    return createList(e)
  })
  return item.name   "-"   name
}

console.log(createList(item))

CodePudding user response：

A simple recursion will do the trick:

let item = {
  id: 1,
  name: "1",
  children: [{
    id: 2,
    name: "2",
    children: [{
        id: 3,
        name: "3",
        children: []
      },
      {
        id: 4,
        name: "4",
        children: []
      }
    ]
  }]
}

var result = []


const createList = (items, acc) => {
  items.forEach(item => {
    const newAcc = {
      id: item.id,
      name: acc ? `${acc.name}-${item.name}` : `${item.name}`
    }
    result.push(newAcc)
    createList(item.children, newAcc)
  })
}

createList([item], null)

console.log(result)

CodePudding user response：

You're on the right track with recursion, but the map function is probably not the best choice for this. Map function doesn't work the way you might expect when there is only one element in the array, as it is not meant to be used to process lists in such a way, but only to "map" data.

Try switching to a for loop or foreach and building the string yourself.

Example:

let sample = {
  id: 1,
  name: "1",
  children: [{
    id: 2,
    name: "2",
    children: [{
        id: 3,
        name: "3",
        children: []
      },
      {
        id: 4,
        name: "4",
        children: []
      }
    ]
  }]
};

function buildArray(input, parentName) {
  let output = [];

  for (let item of input) {
    let name = parentName ? `${parentName}-${item.name}` : item.name;
    output.push({ id: item.id, name: name });
    if (item.children) {
      output = output.concat(buildArray(item.children, name));
    }
  }

  return output;
}

let result = buildArray(sample.children, sample.name);

let output = document.getElementById('myresult');
output.innerText = JSON.stringify(result);

<p id="myresult"></p>