Merging javascript objects (properties+values) into one object

Question

So I've come across this problem when trying to eliminate the need for duplicated data.

Say I've got a list of objects. I'm separating them based on a specific category. And 2 objects return the same data within the Open 'category'. I don't necessarily want to remove the data, so I think merging/combining is the best way?

If Open category, merge all objects. How can I merge objects? I think .concat() is just for arrays. So is this even possible?

...

Open
------
const dupObjects = this.props.response.flight['open'];
// returns objects that look like this...

Object {delta: Array[1], lambda: Array[0], amount: }
Object {delta: Array[1], lambda: Array[0], amount: 200,000} // duplicate lets combine
Object {delta: Array[1], lambda: Array[0], amount: 200,000} // duplicate lets combine



if (category == 'Open'){
    // merge objects
    const dupObjects = this.props.response.flight['open'];
}

Expected output:

Open:
Delta : Information...    Lambda: Information...   Amount: $0
Delta : Information...    Lambda: Information...   Amount: $200,000

Please define merge... do you just want to dedupe, or extend one with another? — Daniel Moses
– Daniel Moses, Commented May 11, 2016 at 16:09
@DMoses not completely sure tbh. but after a quick google search on those terms, I suppose dedupe? — Modelesq
– Modelesq, Commented May 11, 2016 at 16:14
you might find this of interest: stackoverflow.com/questions/171251/… — Regis Portalez
– Regis Portalez, Commented May 11, 2016 at 16:19
@Modelesq Give an example with 3 objects with 2 being the same and the output you would want, otherwise it's hard to tell. Also you may want to look at underscorejs.org for some idea of things that are commonly done. — Daniel Moses
– Daniel Moses, Commented May 11, 2016 at 16:39
Javascript objects do not have "attributes". Do you mean "properties"? — user663031
– user663031, Commented May 11, 2016 at 16:47

Daniel Moses · Accepted Answer · 2016-05-11 17:28:16Z

1

What you are asking is to remove duplicate objects where you define a duplicate as having the same values using a deep equal. See http://underscorejs.org/#isEqual Below is a sample script that does dedupe of the list. It's not very elegant, but it works:

var objects = [
  {"delta":["St.Louis"],"lambda":[],"amount":200000},
  {"delta":["St.Louis"],"lambda":[],"amount":200000},
  {"delta":["Different"],"lambda":[],"amount":200000}
];

var dedupedList = _.reduce(objects, 
 function(result, item) { 
  var isDupe = _.any(result, function(anyItem) { return _.isEqual(item, anyItem); });
  if (!isDupe) result.push(item);
  return result; 
 }, 
 []);

console.log(dedupedList);

<script src="//jashkenas.github.io/underscore/underscore-min.js"></script>

answered May 11, 2016 at 17:28

Daniel Moses

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3 Comments

Modelesq Over a year ago

I really appreciate the answer. Unfortunately I can't use underscore. Since dupObjects's returns each javascript object, I'm just looking to literally combine the 2 or at this point, ignore / remove the duplicate. I'm not sure if it will help me if I post within reactjs channel.

Daniel Moses Over a year ago

I'm not familiar with reactjs. But, conceptually what I have provided should work. You can write your own dedupeCollection function that does a deep equal and removes any that are already there.

Modelesq Over a year ago

Isn't .push for arrays?

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