Js: What happens when curly brackets enclose the variable declaration?

Asked Apr 08 '20 at 07:22

Active Apr 08 '20 at 07:25

Viewed 73 times

I am trying to understand the following expression.

const { TARGET = 'http://localhost:8080', PORT = 80 } = process.env;

How does variable declaration enclosed by curly brackets work? And how does the value assignment for process.env works? Does this type of expression have a name?

asked Apr 08 '20 at 07:22

Dami

This is known as [`Object destructuring`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment#Object_destructuring) – palaѕн Apr 08 '20 at 07:25
in simple terms it is like Unpacking fields/properties from objects – Tapan Dave Apr 08 '20 at 07:26
The assignment within the curly brackets is setting default values which apply if `process.env` does not have the respective property name. – connexo Apr 08 '20 at 07:30
1

Thank you @palaѕн that's really helpful – Dami Apr 08 '20 at 07:34
Thank you @TapanDave for the explanation. – Dami Apr 08 '20 at 07:35
Thank you @connexo for the explanation that resolves my problem. – Dami Apr 08 '20 at 07:35

Js: What happens when curly brackets enclose the variable declaration?

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