从 function 中解构 object

Question

I need some help with return and destructure an object from a function. I want to assign new paras to what ever return from the function.

function someRes() {
const val1 = 1
const val2 = 2
    return {val1, val2}
}

const {val1, val2} = someRes()
const {val3, val4} = someRes()//this returns as undefined

console.log(val1, val2)
console.log(val3, val4) //console.log undefined

I understand that destructure a params is not like assign them to new params but still, Im looking for an elegant way to do it.

thank!

Answer 1

You can use aliases during destructuring. When you use destructuring syntax, the variables created assumes the same name as the corresponding object properties. You can change that using the : while destructuring:

 function someRes() { const val1 = 1 const val2 = 2 return { val1, val2 } } const { val1, val2 } = someRes() const { val1: val3, val2: val4 } = someRes() console.log(val1, val2) console.log(val3, val4)

Answer 2

someRes returns an object with two properties val1 and val2 . Object destructuring requires that you access properties by name so {val3, val4} returns undefined because the object doesn't have those properties.

It looks like you might want to return a tuple instead of an object from your function. Array destructuring is by index so naming is not constrained by property name.

 function someRes() { const val1 = 1; const val2 = 2; return [val1, val2]; } const [val1, val2] = someRes(); const [val3, val4] = someRes(); console.log(val1, val2); console.log(val3, val4);

Otherwise you can alias the second destructuring assignment as mentioned in the other answer

 function someRes() { const val1 = 1; const val2 = 2; return {val1, val2}; } const {val1, val2} = someRes(); const {val1: val3, val2: val4} = someRes(); console.log(val1, val2); console.log(val3, val4);