Appending to a JS object that is not an array?

Question

I have an object that looks something like this

{
  "_id": "DEADBEEF",
  "_rev": "2-FEEDME",
  "name": "Jimmy Strawson",
  "link": "placeholder.txt",
  "entries": {
    "Foo": 0
  }
}

Which is read into my javascript with a $.getJSON call.

So I have the JS object "reply" that holds all this data.

I need to append items such that "entries" becomes extended as follows:

{
  "_id": "DEADBEEF",
  "_rev": "2-FEEDME",
  "name": "Jimmy Strawson",
  "link": "placeholder.txt",
  "entries": {
    "Foo": 0,
    "Bar": 30,
    "Baz": 4
  }
}

I have tried

reply['entries'].push({"Bar": 0});

But that does not work (I presume because nothing is an array)

Can someone provide an alternative method?

Answer 1

With ES2017 you could use:

const input = (
  { _id: 'DEADBEEF'
  , _rev: '2-FEEDME'
  , name: 'Jimmy Strawson'
  , link: 'placeholder.txt'
  , entries: (
      { Foo: 0
      }
    )
  }
)
 
const output = (
  { ...input
  , entries: (
      { ...input.entries
      , Bar: 30
      , Baz: 4
      }
    )
  }
)

console.info(JSON.stringify(output, null, 2))

Note: this will not mutate the original input object, but instead return a new one (typically a good thing).

Answer 2

Here's one more because why not ~ meet Object.assign

let reply = {"_id":"DEADBEEF","_rev":"2-FEEDME","name":"Jimmy Strawson","link":"placeholder.txt","entries":{"Foo":0}};

Object.assign(reply.entries, {
    Bar: 30,
    Baz: 4,
    'Bar Baz': 0
});

console.log('reply =', reply);

Answer 3

reply['entries'].push({"Bar": 0}) does not work as entries is not of type Array but just a plain Object.

Use reply['entries']["Bar"] or reply.entries.Bar. See demo below:

var reply = {
  "_id": "DEADBEEF",
  "_rev": "2-FEEDME",
  "name": "Jimmy Strawson",
  "link": "placeholder.txt",
  "entries": {
    "Foo": 0,
    "Bar": 30,
    "Baz": 4
  }
}
reply['entries']["Bar"] = 0;

console.log(reply);