JavaScript - How to dynamically create a nested array of objects?

Question

I am provided with a string B1-FEOL-SPUTTER-0015, the string will be split up by - (the dash) then used to build up a nested array of objects. This is the original tree:

[{
  "text": "B1",
  "nodes": [{
    "text": "FEOL",
    "nodes": [{
      "text": "SPUTTER"
    }, {
      "text": "COATING"
    }, {
      "text": "EXPOSING"
    }, {
      "text": "DEVELOP"
    }, {
      "text": "PLATING"
    }, {
      "text": "BOND"
    }]
  }, {
    "text": "BEOL",
    "nodes": [{
      "text": "GRINDING"
    }, {
      "text": "BALLDROP"
    }, {
      "text": "PROBING"
    }, {
      "text": "BACKCOATING"
    }, {
      "text": "MARKING"
    }, {
      "text": "SORTING"
    }, {
      "text": "TUG"
    }]
  }]
}, {
  "text": "B2",
  "nodes": [{
    "text": "FEOL",
    "nodes": [{
      "text": "SPUTTER"
    }, {
      "text": "COATING"
    }, {
      "text": "EXPOSING"
    }, {
      "text": "DEVELOP"
    }, {
      "text": "PLATING"
    }, {
      "text": "BOND"
    }]
  }, {
    "text": "BEOL",
    "nodes": [{
      "text": "GRINDING"
    }, {
      "text": "BALLDROP"
    }, {
      "text": "PROBING"
    }, {
      "text": "BACKCOATING"
    }, {
      "text": "MARKING"
    }, {
      "text": "SORTING"
    }, {
      "text": "TUG"
    }]
  }]
}]

I have tried using recursive functions by entering the new values into .forEach(manipulateTree). However I couldn't get it to create new nodes in the array which should be done in the else statement.

import fs from 'fs'
import path from 'path'
import util from 'util'

// This is avaliable in the link below, leading to pastebin
let tree = require('./server/configs/tree.json')

// The values I used to test:

// This works
// const newBranch = 'B1-FEOL-SPUTTER-0015'

// This doesn't
const newBranch = 'B3-ASDF-DSDF987SDF7-0015'

const locations = newBranch.split('-')

let nodes = {}

let iteration = -1
const manipulateTree = branch => {
  iteration++
  // Found node
  if (branch.text === locations[iteration]) {
    // Check if the iteration is second last in the branch array
    if (iteration === locations.length - 2) {
      branch.nodes.push({
        'text': locations[iteration + 1],
        'location': locations.join('-')
      })
    } else {
      // If not then the recursive function will continue operation
      if (branch.nodes && branch.nodes.length > 0) {
        const found = branch.nodes.find(node => node.text === locations[iteration + 1])
        if (found) {
          branch.nodes.forEach(manipulateTree)
        }
      }
    }
  } else {
    console.log('No such node')
    if (iteration === locations.length - 1) {
      branch = {
        'text': locations[iteration],
        'location': locations.join('-')
      }
    } else {
      branch = {
        'text': locations[iteration],
        'nodes': []
      }
    }
  }
  return branch
}

if (tree && tree.length > 0) {
  tree.forEach(manipulateTree)
}

console.log(util.inspect(tree, false, null, true))

The end result that I want is this:

[{
  "text": "B1",
  "nodes": [{
    "text": "FEOL",
    "nodes": [{
      "text": "SPUTTER"
    }, {
      "text": "COATING"
    }, {
      "text": "EXPOSING"
    }, {
      "text": "DEVELOP"
    }, {
      "text": "PLATING"
    }, {
      "text": "BOND"
    }]
  }, {
    "text": "BEOL",
    "nodes": [{
      "text": "GRINDING"
    }, {
      "text": "BALLDROP"
    }, {
      "text": "PROBING"
    }, {
      "text": "BACKCOATING"
    }, {
      "text": "MARKING"
    }, {
      "text": "SORTING"
    }, {
      "text": "TUG"
    }]
  }]
}, {
  "text": "B2",
  "nodes": [{
    "text": "FEOL",
    "nodes": [{
      "text": "SPUTTER"
    }, {
      "text": "COATING"
    }, {
      "text": "EXPOSING"
    }, {
      "text": "DEVELOP"
    }, {
      "text": "PLATING"
    }, {
      "text": "BOND"
    }]
  }, {
    "text": "BEOL",
    "nodes": [{
      "text": "GRINDING"
    }, {
      "text": "BALLDROP"
    }, {
      "text": "PROBING"
    }, {
      "text": "BACKCOATING"
    }, {
      "text": "MARKING"
    }, {
      "text": "SORTING"
    }, {
      "text": "TUG"
    }]
  }]
}, { // This hear is the end result I want if there is no such node from the original tree
  "text": "B3",
  "nodes": [{
    "text": "ASDF",
    "nodes": [{
      "text": "DSDF987SDF7",
      "nodes": [{
        "text": "0015",
        "location": "B3-ASDF-DSDF987SDF7-0015"
      }]
    }]
  }]
}]

I don't understand the end result you want. Are you sure that's the correct pastebin URL? Can you put the desired result in the question instead of a link? — Barmar
– Barmar, Commented Jan 19, 2019 at 1:03
You're just given B1-FEOL-SPUTTER-015, where is all the rest of that result coming from? — Barmar
– Barmar, Commented Jan 19, 2019 at 1:07
forEach doesn't do anything with the return value of the callback function, what's the point of return branch? — Barmar
– Barmar, Commented Jan 19, 2019 at 1:10
You're taking a tree that's already in the JSON file, then this function is supposed to add something new to it from that string? It's hard to understand precisely what you're trying to add. Can you post a simple input tree and explain what you're trying to add to it? — Barmar
– Barmar, Commented Jan 19, 2019 at 1:27

Mark · Accepted Answer · 2019-01-19 02:00:50Z

Given the tree structure and a path, you just need to iterate the path and keep track of where you are. If you end up someplace that doesn't exist yet add it and continue. You can keep track of the index so you know when you've hit the last item and should add the location rather than the nodes array:

let tree = [{"text": "B1","nodes": [{"text": "FEOL","nodes": [{"text": "SPUTTER"}, {"text": "COATING"}, {"text": "EXPOSING"}, {"text": "DEVELOP"}, {"text": "PLATING"}, {"text": "BOND"}]}, {"text": "BEOL","nodes": [{"text": "GRINDING"}, {"text": "BALLDROP"}, {"text": "PROBING"}, {"text": "BACKCOATING"}, {"text": "MARKING"}, {"text": "SORTING"}, {"text": "TUG"}]}]}, {"text": "B2","nodes": [{"text": "FEOL","nodes": [{"text": "SPUTTER"}, {"text": "COATING"}, {"text": "EXPOSING"}, {"text": "DEVELOP"}, {"text": "PLATING"}, {"text": "BOND"}]}, {"text": "BEOL","nodes": [{"text": "GRINDING"}, {"text": "BALLDROP"}, {"text": "PROBING"}, {"text": "BACKCOATING"}, {"text": "MARKING"}, {"text": "SORTING"}, {"text": "TUG"}]}]}]

const newBranch = 'B3-ASDF-DSDF987SDF7-0015'

let components = newBranch.split('-') 

let nodes = tree                                    // nodes is the current array
components.forEach((text, i) => {
    let current = nodes.find(i => i.text == text )  // find matching item
    if (!current) {
        current = i == components.length - 1        // if no matching item add it 
          ? {text, location: newBranch }
          : {text, nodes:[] }
        nodes.push(current)
    }
    else if (!current.nodes) current.nodes = []          
    nodes = current.nodes  
})

console.log(tree)

Thank you Mark, that really helped. I didn't think it would be that simple, I really over-complicated the problem

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