What is the effect of const object = this.variable?

Question

I'm working on a react-native app which was initially developed by a remote company. In this project I found the following code:

class SomeScreen extends Component { constructor { this.state = { connection: null codeInput: '', paramInput: '', } } someFunction() { const { connection, codeInput: code, paramInput: params, } = this.state this.otherFunction(connetion.var, parseInt(code), parseInt(params)) } }

I'm wondering what the const {} = this.variable does. I've never seen this way of assigning and I'm wondering if it's the same as

this.state.code = code; this.state.params = params;

Possible duplicate of Object destructuring syntax - ES6

31piy
– 31piy

2018-08-21 11:17:17 +00:00
Commented Aug 21, 2018 at 11:17 — 31piy
– 31piy, Commented Aug 21, 2018 at 11:17

Alex T · Accepted Answer · 2018-08-21 11:22:32Z

2

Consider the code snippet below to understand your code. Basically you are just making a copy to a const variable.

let obj = {a:1, b:2, c:3} const {a} = obj; console.log(a); obj.a = 4; console.log(obj.a); console.log(a);

answered Aug 21, 2018 at 11:22

Alex T

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3 Comments

Thomas Stubbe Over a year ago

So if I understand right it's the opposite of what I supposed and the same as const params = this.state.params; const code = this.state.code; const connection = this.state.connection;

Alex T Over a year ago

Yes, exactly. Assignment operator works right to left even in JS.

Thomas Stubbe Over a year ago

Thanks! So this piece of code has no effect whatsoever, just call the function without the needless assign (since it are strings and copied by value)

Murat Taştemel · Accepted Answer · 2018-08-21 11:31:21Z

It is Object Destructuring. Therewith you can unpack from values from arrays or properties from object. You can click link for more detailed information Object Destructuring Info

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