spread operator on array object does not emit properties

Question

How do i define an array object with a propery that will be emitted when using a spread operator, if such thing is even possible (and why if it is not?).

I'm using arrays in a redux app so when I'm updating a store with a return {...state,newElement} i lose the properties of the arrays in my state.

for example:

    const object1 = [1,2,3];

Object.defineProperty(object1, 'pizza', {
  value: 30,
  writable: true,
  enumerable:true,
  configurable:true
});


console.log(...object1);
// output: 1 2 3

// my expected output: 1 2 3 30

thanks

Answer 1

The actual iterator of your hybrid object-array is the Array's one (which is Array.prototype.values ):

 const arr = []; console.log(arr.values === arr[Symbol.iterator])

If you want to have an hybrid object-array, and expect it to be fully iterable, you have to write the iterator yourself in order to override the Array's one:

 const object1 = [1,2,3]; Object.defineProperty(object1, 'pizza', { value: 30, writable: true, enumerable:true, configurable:true }); object1[Symbol.iterator] = function* () { // Write whatever implementation you need for(const key in this) { yield this[key]; } } console.log(...object1); // output: 1 2 3 30