javascript - coping object element

Question

I'm trying to copy the name from one object to another as below:

console.log(this.source.name)

//gives "mike"

mounted: function() {
   this.client.name = Object.assign({}, this.source.name)
}

then

console.log(this.client.name)

//gives object with 1: m, 2: i, 3: k, 4:e

What I'm doing wrong? How should I correct my code?

Possible duplicate of [How to force JavaScript to deep copy a string?](https://stackoverflow.com/questions/31712808/how-to-force-javascript-to-deep-copy-a-string) — Federico klez Culloca, Mar 02 '18 at 08:52
@FedericoklezCulloca maybe but I don't understand this example — gileneusz, Mar 02 '18 at 08:54
`Object.assign({}, 'mike')` – how would you expect the resulting object to have an attribute `mike` with a value? — deceze, Mar 02 '18 at 08:54
@Dencio okay guys, I'm js newbie, I wanted just to copy element of the object, when I copied objects in the past, I got wrong results so I started to using Object.assign function :) — gileneusz, Mar 02 '18 at 08:58

Amanshu Kataria · Accepted Answer · 2018-03-02T09:21:49.450

1

Object.assign takes two object params, but you're passing a string to second param. So, if you want to assign string value simply do this.client.name = this.source.name.

If you want to copy object value, use Object.assign and store an object in this.source.name as this.source.name={"key":"value"};.

edited Mar 02 '18 at 09:21

answered Mar 02 '18 at 08:58

Amanshu Kataria

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this is the right answer, Object assign could be used but not in this case. Thanks for valuable advice – gileneusz Mar 02 '18 at 09:09
@gileneusz Just console and then check the documentation when such thing happens. – Amanshu Kataria Mar 02 '18 at 09:11
2

This has the downside of creating a reference. Change `this.source.name` and `this.client.name` will also change. That may be wanted or not, but it should be noted. – connexo Mar 02 '18 at 09:13
@connexo `this.client.name = this.source.name` refers to assigning string value, not the object. – Amanshu Kataria Mar 02 '18 at 09:17
@connexo this is why I tried to use Object.assign function. I wanted to avoid this.source.name changes to affect this.client.name later on – gileneusz Mar 02 '18 at 09:17
`name` might be as well be an `object` looking similar to this `{ firstName: "Peter", lastName: "Molyneux", middleName: "" }` – connexo Mar 02 '18 at 09:20
@connexo it depends on what exactly you want to perform. – Amanshu Kataria Mar 02 '18 at 09:23
1

I'm not saying you're doing anything wrong, I'm just pointing out potential issues. – connexo Mar 02 '18 at 09:23
Oh! okay. Yeah, that's true. directly assigning object will lead to the issue you mentioned. – Amanshu Kataria Mar 02 '18 at 09:24
1

thank you guys for a valuable discussion. I learned a lot from it, and you are both right :) – gileneusz Mar 02 '18 at 09:24

score 1 · Answer 2 · answered Mar 02 '18 at 09:07

1

You can use the following adjustment:

this.client = Object.assign({}, this.client,  {name: this.source.name})

answered Mar 02 '18 at 09:07

connexo

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thanks for this answer, this is also correct and could be used on arrays inside object element (?) – gileneusz Mar 02 '18 at 09:10
Doesn't matter what type of data `this.source.name` holds. – connexo Mar 02 '18 at 09:11
so this way is more universal. I will keep @AmanshuKataria answer as a correct because it's more simpler and easy to use – gileneusz Mar 02 '18 at 09:13

score 0 · Answer 3 · edited Mar 02 '18 at 09:09

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I would use the ES6 spread operator syntax for this

const b = {iam b}
const a = {...b}
console.log(a) // {iam b}

edited Mar 02 '18 at 09:09

connexo

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answered Mar 02 '18 at 09:07

Paulquappe

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As you can see, you must have missed something. – connexo Mar 02 '18 at 09:09

javascript - coping object element

3 Answers3