为了获得对象的第一个属性而进行的结构分解？

Question

For arrays, we can define the properties depending on it's indexes like:

 const arr = [1, 2, 3]; const [first, second, third] = arr; console.log(first, second, third) 

I'm just wondering if there's a possible solution to do it's reverse with objects like:

 const obj = {first: "a", second: "b", third: "c"} const {0, 1, 2} = obj; //expected: "a", "b", "c" 

Answer 1

It isn't.

Objects are not designed to be ordered, so there isn't a first property per se.

You could convert an object into an array of its values first …

 const obj = { first: "a", second: "b", third: "c" } const array = Object.values(obj); const [foo, bar, baz] = array; console.log({ foo, bar, baz }); 

… but it is unlikely to be useful and it certainly wouldn't be intuitive code that is easy to maintain.

Answer 2

You do it like this for objects:

const obj = {foo: 123, bar: 'str'}

const {foo, bar} = obj

Answer 3

Try this:

const obj = {first: "a", second: "b", third: "c"}
const indexes = [0, 1, 2]
indexes.map( (val) => { return Object.values(obj)[val] } ) //["a", "b", "c"]

Answer 4

You could take the values and assign this to an array for destructuring.

The order is actually dtermined by the insertation order or if a key is like a valid index of an array, it is sorted numerically to top.

 const object = { first: "a", second: "b", third: "c" }, [first, second, third] = Object.values(object); console.log(first, second, third); 

For extracting a an arbitrary position, you vould take an object with an index an object property assignment pattern [YDKJS: ES6 & Beyond] for a new valid variable.

 const object = { first: "a", second: "b", third: "c" }, { 2: foo } = Object.values(object); console.log(foo);