Iterate through nested JSON object array and store as key-value pair

Question

I have to iterate through this JSON:

{
  "data": 321563,
  "group": [
    {
      "added": 42421,
      "normal": {
        "x": 39,
        "y": "0.1300",
        "b": "0.4326",
        "c": "0.0552",
        "f": 166833
      },
      "j": "240313",
      "b": "0.2251",
      "a": "dda",
      "b": "0.101",
      "a": 922,
      "f": {
        "c": 39,
        "d": "0.263",
        "a": "2.8955",
        "h": "0.3211",
        "d": 274
      },
      "a": false,
      "k": 5,
      "w": "0.072",
      "d": "0.045",
      "e": 3
    },

I only want the j and k stored like a key value pair e.g. "j":k

I need to loop all of it, and store it to a file.

What specifically are you having problems with? Do you know how to iterate over an array? — Felix Kling, Mar 18 '19 at 20:19
Possible duplicate of [Access / process (nested) objects, arrays or JSON](https://stackoverflow.com/q/11922383/218196) — Felix Kling, Mar 18 '19 at 20:51
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Get Off My Lawn · Accepted Answer · 2019-03-18T20:29:00.397

0

You can use a map to get a new array of items, this will not affect the old array.

const data = {
  "game_count": 8750,
  "sets": [
    {
      "appid": "221540",
      "true_count": 9,
      "bgs_avg": "0.10",
      // Other data here
    },
    {
      "appid": "123456",
      "true_count": 9,
      "bgs_avg": "0.20",
      // Other data here
    }
  ]
}


// Use "data.sets = data.sets.map(...)" to replace the data
// The following will only assign to a new variable
const newArray = data.sets.map(itm => { return {appid: itm.appid, true_count: itm.true_count} })

console.log(newArray)

We can also take the data and assign it directly back to the original overwriting it just by using data.sets = data.sets.map(...) as seen here:

const data = {
  "game_count": 8750,
  "sets": [
    {
      "appid": "221540",
      "true_count": 9,
      "bgs_avg": "0.10",
      // Other data here
    },
    {
      "appid": "123456",
      "true_count": 9,
      "bgs_avg": "0.20",
      // Other data here
    }
  ]
}

data.sets = data.sets.map(itm => { return {appid: itm.appid, true_count: itm.true_count} })

console.log(data)

edited Mar 18 '19 at 20:29

answered Mar 18 '19 at 20:22

Get Off My Lawn

34,175
38
176
338

you have your format for map wrong, when returning an object literal you need to wrap it within braces, you can't do shorthand `itm => { return {...} }` – Get Off My Lawn Mar 18 '19 at 20:30
Otherwise do `itm => new Object({appid: itm.appid, true_count: itm.true_count})` – Get Off My Lawn Mar 18 '19 at 20:33
Just the extra parentheses are enough to get the arrow expression working. – trincot Mar 18 '19 at 20:37
you are setting data to an empty object then trying to access `sets` which isn't in that object because it is empty. – Get Off My Lawn Mar 18 '19 at 21:04

score 0 · Answer 2 · edited May 06 '19 at 18:46

0

In simple javascript this should work -

let newObj = {}
for(let i=0; i<obj.group.length; i++){
  newObj[obj.group[i].j] = obj.group[i].k 
}

Where 'obj' is your object

newObj will be you new Object which will contain all the key value pair

edited May 06 '19 at 18:46

Spaceglider

97
11

answered Mar 18 '19 at 20:25

Shaurya Mittal

764
1
8
19

Iterate through nested JSON object array and store as key-value pair

2 Answers2