Can I destructure a property named after an integer, on an object?

Question

Can I destructure a property named after an integer, on an object?

const { 0 } = { ['0']: 'foo' } // doesn't work

// or

const arr = ['foo']
const { 0, length } = arr // doesn't work

Answer 1

0 is not a valid identifier (variable name). You'll have to put it into some other variable name instead:

const { 0: containsFoo } = { ['0']: 'foo' };
console.log(containsFoo);

const arr = ['foo'];
const { 0: containsFoo, length } = arr;
console.log(containsFoo);

Answer 2

Yes, but you must supply a name for the property to be destructured into because an integer is not a valid identifier. For example:

const { 0: zero } = { ['0']: 'foo' }
console.log(zero)

and,

const arr = ['foo']
const { 0: zero, length } = arr
console.log(zero, length)

This is useful for methods like String#matchAll:

const matches = 'foo'.matchAll(/o/gi)
for(let {0: item, index} of matches)
    console.log(item, index)

Answer 3

You can't do var 0 = "something" so you won't be able to do that with any kind syntactical variety;