Dynamically parsing JSON arrays in JavaScript

Question

I'm trying to parse a JSON file stored locally on my machine in JavaScript in discord.js (v12). This JSON has several keys and values:

{
    "name": "Robert",
    "rank": "Owner",
    
    "hobbies": [{
        "id": 1,
        "name": "gaming"
    }, {
        "id": 2,
        "name": "listening to music"
    }, {
        "id": 3,
        "name": "vibing"
    }, {
        "id": 4,
        "name": "driving down the highway"
    }],

    "roles": [{
        "id": 1,
        "name": "Founder"
    }, {
        "id": 2,
        "name": "Premium Member"
    }]
}

I want to send the above in a message on Discord as follows:

name: Robert
rank: Owner
hobbies: gaming, listening to music, vibing, driving down the highway
roles: Founder, Premium Member

I also want this to be dynamic. Meaning my code should adapt if a new key and value is added to the current set.

With the current code used, this is my result:

name: Robert
rank: Owner
hobbies: gaming, listening to music, vibing, driving down the highway

This is my current code:

let noted = ``
var raw = fs.readFileSync(name)
var obj = JSON.parse(raw)
    
for (var item in obj) {

    if (obj[item] instanceof Object) {
        for (var i in obj.hobbies) {
            noted += `${obj.hobbies[i].name}, `
        }
    } else {
        noted += `${item}: ${obj[item]}\n`
        noted += `hobbies: `
    }
}

message.channel.send(noted)

The variable name is const name = require("./names.json"); at the top of the code.

This code works fine with name, rank and hobbies.

roles has to be manually checked in the for loop if I want it to be visible. My goal is to cause any new keys to be added to be automatically detected and added into the noted variable.

I've seen something similar done using map(), but I tried it without getting anywhere good. This is rather sloppy code as well but I'm not interested in keeping it clean.

blex · Accepted Answer · 2021-01-15 23:18:41Z

1

You could do something like this with map and join:

const obj = {"name":"Robert","rank":"Owner","hobbies":[{"id":1,"name":"gaming"},{"id":2,"name":"listening to music"},{"id":3,"name":"vibing"},{"id":4,"name":"driving down the highway"}],"roles":[{"id":1,"name":"Founder"},{"id":2,"name":"Premium Member"}]};

const noted = Object.entries(obj)
                    .map(([key, val]) =>
                      `${key}: ${
                        val instanceof Array ? val.map(x => x.name).join(', ') : val
                       }`)
                    .join('\n');

console.log(noted);

answered Jan 15, 2021 at 23:18

blex

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Comments

vincent · Accepted Answer · 2021-01-16 08:36:42Z

Here is an iterative solution using object-scan.

I find it a bit easier to read, but most importantly it is very flexible as to which keys you want to traverse.

// const objectScan = require('object-scan');

const myData = { name: 'Robert', rank: 'Owner', hobbies: [{ id: 1, name: 'gaming' }, { id: 2, name: 'listening to music' }, { id: 3, name: 'vibing' }, { id: 4, name: 'driving down the highway' }], roles: [{ id: 1, name: 'Founder' }, { id: 2, name: 'Premium Member' }] };

const convert = (data) => {
  const r = objectScan(['*', '*[*].name'], {
    reverse: false,
    filterFn: ({ isLeaf, context, key, value }) => {
      if (isLeaf) {
        if (!(key[0] in context)) {
          context[key[0]] = value;
        } else {
          context[key[0]] += `, ${value}`;
        }
      }
    }
  })(data, {});
  return Object.entries(r).map(([k, v]) => `${k}: ${v}`).join('\n');
};

console.log(convert(myData));
/* =>
name: Robert
rank: Owner
hobbies: gaming, listening to music, vibing, driving down the highway
roles: Founder, Premium Member
 */

.as-console-wrapper {max-height: 100% !important; top: 0}

<script src="https://bundle.run/[email protected]"></script>

Disclaimer: I'm the author of object-scan

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