How to increment and add the new ID to a new node in a Json array tree structure using Nodejs

Question

we have an array like this. I want to add the new child and increment the "id".

[  
   {  
      "name":"Headcount",
      "id":1,
      "parentId":0,
      "is_open":true,
      "children":[  
         {  
            "name":"temp1",
            "id":2,
            "parentId":1,
            "is_open":true,

         },
         {  
            "name":"Temp",
            "id":90
         }
      ]
   },
{  
      "name":"temp2",
      "id":4,
      "parentId":0,
      "is_open":true,
      "children":[  
         {  
            "name":"temp3",
            "id":5,
            "parentId":4,
            "is_open":true,
            "children":[  
               {  
                  "name":"temp4",
                  "id":6,
                  "parentId":5,
                  "is_open":true   }
      ]
   }
]

We want to add a new ID to the newly added child node.

we have tried adding the new id by finding the max value in an array and add it to the new child node.

the code we tried is

var res = Math.max.apply(Math,data.map(function(o){return o.id;}))
         console.log("Max ID res:"+res);

It gives the answer as "4" but we want it "90" since it is the largest number. how to iterate through Child nodes and find/increment the new "id".

Thanks in advance for your help.

Answer 1

Not fully fleshed out but the general idea goes as follows: Since it's a heavily nested structure we avoid recursion or any deep search by transforming the structure into a string and traverse it then via regex.

First we get all "id" entries which we then use as starting points for new matches that return us the digits after each index. Then on those numbers we apply a reduce to find the maximum and we are done. You can now apply the number into your new structure.

I wasn't sure which part of the structure is part of the to be searched part so I just searched the whole structure for the highest id there is.

 let data = [ { "name":"Headcount", "id":1, "parentId":0, "is_open":true, "children":[ { "name":"temp1", "id":2, "parentId":1, "is_open":true, }, { "name":"Temp", "id":90 } ] }, { "name":"temp2", "id":4, "parentId":0, "is_open":true, "children":[ { "name":"temp3", "id":5, "parentId":4, "is_open":true, "children":[ { "name":"temp4", "id":6, "parentId":5, "is_open":true } ] } ] }] let f = (data) => { // https://stackoverflow.com/a/3410557/9758920 let s = JSON.stringify(data), regex = /"id"/gi, result, indices = []; while ( (result = regex.exec(s)) ) { indices.push(result.index); } let ids = [] for (i of indices) { ids.push(s.slice(i,i+10).match(/\\d+/g)[0]) // not optimal by any means } return ids.reduce((m,c) => (m > c) ? m : c) } console.log(f(data))

The following should be a bit quicker:

let f = (data) => {
  return JSON.stringify(data)
          .match(/"id":\d+/g)
          .reduce((m,c) => {
            let tmp = +c.slice(5);
            return (m > tmp) ? m : tmp})
}