Assignment to Multiple Variables in JavaScript

Question

Can properties of an object somehow be assigned to multiple variables in JavaScript with a single call (for convenience)?

function getValues() {
    return {
        first: 1,
        second: 2
    };
}

function convenientAssignment() {
    let first = 0;
    let second = 0;
    {first, second} = getValues(); // <-- How can this be achieved?
    console.log("Values:", first, second);
}

Without using separate assignments like the following:

let values = getValues();
first = values.first;
second = values.second;

This question has nothing to do with concurrency.

Why do you need this? Is it because of some (perceived) concurrency problem, or just for convenience? — Tim Biegeleisen
– Tim Biegeleisen, Commented Aug 15, 2018 at 11:47
developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — Kirk Larkin
– Kirk Larkin, Commented Aug 15, 2018 at 11:48
@TimBiegeleisen Just conveniency. I have updated the question. — Snackoverflow
– Snackoverflow, Commented Aug 15, 2018 at 11:51

conradj · Accepted Answer · 2018-08-15 15:02:10Z

3

You were very close, Use object destructuring to get an objects values into variables.

function simultaneous() {
    const {first, second} = getValues(); // <-- et voila!
    console.log("Values:", first, second);
}

In your example, where your variables were already declared, you can do:

function convenientAssignment() {
    let first = 0;
    let second = 0;
    ({first, second} = getValues()); // <-- et voila!
    console.log("Values:", first, second);
}

edited Aug 15, 2018 at 15:02

answered Aug 15, 2018 at 11:50

conradj

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2 Comments

Snackoverflow Over a year ago

What if the variables have been declared before, for example class members?

Snackoverflow Over a year ago

Thank you! Great! It was difficult to google this.. Now I know it is called object destructuring.

Sirko · Accepted Answer · 2018-08-15 11:50:24Z

3

This is pretty much what a destructuring assignment is supposed to do:

function getValues() {
    return {
        first: 1,
        second: 2
    };
}

let { first, second } = getValues();

console.log( first, second );
// 1 2

answered Aug 15, 2018 at 11:50

Sirko

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Comments

Strelok · Accepted Answer · 2018-08-15 11:57:41Z

1

In your particular case since you've already declared first and second you need to wrap the descructuring assignment in brackets () like so:

function getValues() {
    return {
        first: 1,
        second: 2
    };
}

function convenientAssignment() {
    let first = 0;
    let second = 0;
    ({first, second} = getValues()); // <-- Note the (...)
    console.log("Values:", first, second);
}

Because {first, second} by itself is considered a block.

answered Aug 15, 2018 at 11:57

Strelok

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