How to add value to an object which is inside an array in JavaScript?

Question

I have an array with multiple object into it,

const tokens = 
      [ { to: "abc", sound: "default" } 
      , { to: "def", sound: "ring"    } 
      , { to: "ghi", sound: "vibrate" } 
      ]

Further i want to add 2 different value say title and body to each object something like this :-

Note:- I have more than 300-400 objects in array "tokens" so please try to reply with an efficient code

const tokens = 
      [ { to: "abc", sound: "default", title: "test", body: "test2" } 
      , { to: "def", sound: "Ring",    title: "test", body: "test2" } 
      , { to: "ghi", sound: "vibrate", title: "test", body: "test2" }
      ]

Please Let me know how this can be done in JavaScript ?

both will work for me, if possible let me know for both the ways.(there are 300-400 objects in array so try with an efficient way) — Adarsh Jaiswal, Feb 22 '20 at 21:24

score 3 · Accepted Answer · answered Feb 22 '20 at 21:26

3

You could take a non mutate approach and get a new array with new objects without altering the given data.

var tokens = [{ to: "abc", sound: "default" }, { to: "def", sound: "Ring" }, { to: "ghi", sound: "vibrate" }],
    result = tokens.map(o => ({ ...o, title: "test", body: "test2" }));

console.log(result);

answered Feb 22 '20 at 21:26

Nina Scholz

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Isn't creating new objects slower than writing to the same object? – TheMaster Feb 22 '20 at 22:55
@TheMaster, yes it is. does it matter? – Nina Scholz Feb 23 '20 at 09:52
I mean op said, *so please try to reply with an efficient code*. So, I was wondering if it is efficient. You specifically mentioned *non mutate approach*. So, just wondering if I'm missing something. – TheMaster Feb 23 '20 at 10:21

Mister Jojo · Answer 2 · 2020-02-22T21:43:06.550

you can also use this way

const tokens = 
      [ { to: "abc", sound: "default" } 
      , { to: "def", sound: "ring"    } 
      , { to: "ghi", sound: "vibrate" } 
      ] 


tokens.forEach(e=>{ e.title= "test"; e.body= "test2" })

console.log( tokens )

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

an other way:

const tokens = 
      [ { to: "abc", sound: "default" } 
      , { to: "def", sound: "ring"    } 
      , { to: "ghi", sound: "vibrate" } 
      ] 
      newElements = {title:'test', body:'test2'}
      ;
tokens.forEach(e=>Object.assign(e, newElements))

console.log( tokens )

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

How to add value to an object which is inside an array in JavaScript?

2 Answers2