How to mix const and let when using object or array destructuring assignment in ES6?

Question

Example :

const foo = {a: "A", b: "B"}
const {a, b} = foo

What if I want b to be a variable using let ?

score 57 · Accepted Answer · answered Nov 13 '17 at 12:06

57

It seems like you can't differentiate variable's declaration in a one line. However, you could split it into two lines and use a different variable declaration, depends on which variable you want to get.

const { a } = foo; 
let { b } = foo;

answered Nov 13 '17 at 12:06

kind user

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if I want to de-structure a function call, I need 3 lines to do it and to come up with an intermediary variable name – Boris Verkhovskiy Apr 21 '22 at 06:15
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The sucky scenario that this answer doesn't call out in the code example is `...rest`. – mellis481 May 06 '22 at 19:06

drazewski · Answer 2 · 2018-12-18T12:31:58.343

If you want to use array destructuring assignment with const and let you can use elision. Let's consider an example:

const [a, b, c] = foo;

If you want to 'a' be a let, and 'b' and 'c' const, you can write:

let [ a ] = foo;
const [, b, c] = foo;

Another way is to use the fact that array is an object. So you can write it also like this:

let [a] = foo;
const {1: b, 2: c} = foo;

All about destructing can be find here: http://exploringjs.com

How to mix const and let when using object or array destructuring assignment in ES6?

2 Answers2