Adding new property to every object of array using spread operator does not work

Question

I have an array of objects with binary Files like this

[{item: File},{item: File},{item: File}]

and i need to add new key/value to every obj. I tried doing it with mapping an array and concatenating new property 'description' with existing 'name':

arr.map((el) => ({ ...el, description: '' }))

so it should look like this:

[{item: File, description: ''},{item: File, description: ''},{item: File, description: ''}].

But when i try to do this, it only returns a description without name:

Are you sure your original objects have name properties to begin with? What you have showed should work. Please provide a minimal reproducible example. — Felix Kling
– Felix Kling, Commented Jun 24, 2020 at 9:25
My bad. Initially i tried to add description to object with binary File. Edited it — msobolev
– msobolev, Commented Jun 24, 2020 at 9:41

saeed eivazi · Accepted Answer · 2020-06-24 09:44:30Z

6

maybe you forgot to assign 'map'

returned value to your object. lets do it:

let arr = [{name: '1'},{name: '2'},{name: '3'}]
arr = arr.map( item => ({ ...item, description:'' }) )
console.log(arr)

result is :

0: {name: "1", description: ""}
1: {name: "2", description: ""}
2: {name: "3", description: ""}

answered Jun 24, 2020 at 9:44

saeed eivazi

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1 Comment

Felix Kling Over a year ago

Well, the image shows that the object has a description property...

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