Object destructuring: Assign null values in one line

Assuming I have an object like this

foo = {
    a: 1,
    b: 2,
    c: 3
};

I would destructure it this way

const {a, b, c} = foo;

However, what, if the keys a, b and c do not exist?

foo = null;

This won’t work then

const {a, b, c} = foo;

I would have to do something like

let a, b, c;

if(foo) {
    a = foo.a;
    b = foo.b;
    c = foo.c;
};

Is there a way to do this in one line? Something like

 const {a, b, c} = foo ? foo : null; // this is not working

null is not an object. (evaluating ‘_ref2.a’)

>Solution :

When foo is not an object, you are going to have to give it an object so the destructuring can happen. So set it to an empty object using an ‘or’. Now if foo is defined it will use foo, if it is not defined it will use the default object.

const foo = undefined;
const { a, b, c } = foo || {};
console.log(a, b, c);

If you want default values, set them in the object.

const foo = undefined;
const { a, b, c } = foo || {a : 'a', b: 'b', c: 'c' };
console.log(a, b, c);

If you want default values if the object does not provide them all, you can set values in the destructuring.

const foo = { a: 1};
const { a = "a", b = "b", c = "c" } = foo || {};
console.log(a, b, c);