Compare two objects in JavaScript

Question

I have constructed objects as follow:

Object 1

[ { 
   ext: '1287',
   ip: '(Unspecified)',
   queue: [ ]
 } ]

Object 2

 [ { Queue: '222',
    Members:
     [ {"ext":"1287"},
       {"ext":"4118"} ],
    Callers: [] },

  { Queue: '111',
    Members:
     [ {"ext":"4131"},
       {"ext":"1287"},
       {"ext":"4138"}
     ],
    Callers: [] }]

I want to compare Object 1 and Object 2. If the value of ext key from Object 1 exists in the nested Members object of Object 2 then the value of Queue should be pushed to a queue array and the final object should be like as shown below.

Final Object that I want

   [{ ext: '1287',
   ip: '(Unspecified)',
   queue: [222, 111 ] }]

I need some hints regarding how a nested object like this is compared using lodash.

'{"ext":"4131"}' is a string in the question. Is it a typo? — Nikhil Aggarwal
– Nikhil Aggarwal, Commented Sep 12, 2018 at 11:39
a) There is no such thing as JSON objects. b) You show arrays, not objects. c) Your JSON is invalid, property names b must be quoted in JSON. — connexo
– connexo, Commented Sep 12, 2018 at 11:40
'{"ext":"4131"}', '{"ext":"1287"}', '{"ext":"4138"}' object 2 is members are array of string OR each behaving as an individual object — Siddharth Jain
– Siddharth Jain, Commented Sep 12, 2018 at 11:42

Nikhil Aggarwal · Accepted Answer · 2018-09-12 12:26:12Z

3

You can try following using Array.forEach and Array.some

let obj1 = [{ext: '1287',ip: '(Unspecified)',queue: []}];
let obj2 = [{Queue: '222',Members: [{"ext":"1287"},{"ext":"4118"}],Callers: []},{Queue: '111',Members: [{"ext":"4131"},{"ext":"1287"},{"ext":"4138"}],Callers: []}];

obj1.forEach(o => {
  obj2.forEach(v => {
    let exists = v.Members.some(m => m.ext === o.ext);
    if (exists) o.queue.push(v.Queue);
  });
});

console.log(obj1);

Improvement

You can improve the performance by first creating a map of obj1 with ext as key and object as value. Use Array.reduce and Object.assign

let obj1 = [{ext: '1287',ip: '(Unspecified)',queue: []}];
let obj2 = [{Queue: '222',Members: [{"ext":"1287"},{"ext":"4118"}],Callers: []},{Queue: '111',Members: [{"ext":"4131"},{"ext":"1287"},{"ext":"4138"}],Callers: []}];

let map = obj1.reduce((a, c) => Object.assign(a, {[c.ext] : c}), new Map());

obj2.forEach(v => {
  v.Members.forEach(m => {
    if(map[m.ext]) map[m.ext].queue.push(v.Queue);
  });
});

console.log(obj1);

edited Sep 12, 2018 at 12:26

answered Sep 12, 2018 at 11:47

Nikhil Aggarwal

28.5k4 gold badges46 silver badges61 bronze badges

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2 Comments

node_man Over a year ago

Thanks, Nikhil. This solution is perfect. Also, I corrected my question

Nikhil Aggarwal Over a year ago

@NAVLEPRAVIN - Glad to help you!

marzelin · Accepted Answer · 2018-09-12 12:14:15Z

1

Solution without mutations:

const obj1 = [{ext: '1287',ip: '(Unspecified)',queue: []}];
const obj2 = [{Queue: '222',Members: [{"ext":"1287"},{"ext":"4118"}],Callers: []},{Queue: '111',Members: [{"ext":"4131"},{"ext":"1287"},{"ext":"4138"}],Callers: []}];

const hasExt = ext => o2 => o2.Members.some(m => m.ext === ext)

const result = obj1.map(o1 => {
  const newQueue = obj2
    .filter(hasExt(o1.ext))
    .map(m => m.Queue);
    
  return { ...o1, queue: [...o1.queue, ...newQueue] };
})

console.log(result);

answered Sep 12, 2018 at 12:14

marzelin

11.7k5 gold badges38 silver badges50 bronze badges

8 Comments

node_man Over a year ago

Hey this solution is also very helpful. Thank you

node_man Over a year ago

Hey how do I do it if I want the array like this [ { "ext": "1287", "ip": "(Unspecified)", "queue": [ {"number" : "222"}, {"number" : "111"} ] } ]

marzelin Over a year ago

@pravinnavle change .map(m => m.Queue) to .map(m => ({number: m.Queue}))

node_man Over a year ago

Thanks a lot, it worked. Sorry I'm accepting more and more help.

marzelin Over a year ago

@pravinnavle .map(m => ({number: m.Queue, name: m.Members.find(m => m.ext === o1.ext).name})) best resource for web platform is developer.mozilla.org. If you want to go deep with js -> github.com/getify/You-Dont-Know-JS. or videos at frontendmasters.com (all courses are free to watch this week)

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