Javascript appending object doesn't guarantee order

I have looked at this question in stack overflow about objects guaranteeing order.
https://stackoverflow.com/questions/5525795/does-javascript-guarantee-object-property-order

some says they guarantee, some says they don't, depending on situations. Meantime I've encountered following problem.

I have an array of objects, similar to below:

const arrayObject = [
{id:'a123', bar:'hello'}, 
{id:'a321', bar: 'foo'} ];

now I wish to turn this arrayObject into object of object, with structure as follows with the same order as the array:

const object = {
   'a123': {id:'a123', bar:'hello'},
   'a321': {id:'a321', bar: 'foo'},
}

basically using the id of each item in the array as the key of the object. Below is the code I used to try to achieve it:

let newObj = {};
arrayObject.forEach(data=>{
   const temp = {
     [data.id]:{
        id: data.id,
        bar: data.bar
     },
   };
   newObj={...newObj, ...temp};
})

I do get the correct structure, however the order is not the same as the order of arrayObject, i.e. it returns:

const object = {
   'a321': {id:'a321', bar: 'foo'},
   'a123': {id:'a123', bar:'hello'},
}

I've tried with more items in the array, and I get same result. It does not guarantee the order.

Is there something wrong with my code, or is it simply not guaranteeing the order?

What do I have to do to make the object be the same order as the array?

Preserve the order by including ordering information in the (unordered) object. Anytime later, when you need to recover the original order, use the saved ordering information...

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

const arrayObject = [{
    id: 'a123',
    bar: 'hello'
  },
  {
    id: 'a321',
    bar: 'foo'
  }
];

let object = {}
arrayObject.forEach((e, i) => {
  object[e.id] = { ...e, orderWith: i } // the index will tell us how to sort later
})

// later on
let sorted = Object.values(object).sort((a, b) => a.orderWith - b.orderWith)
console.log(sorted)

<!-- end snippet -->

I think what you're looking for is a Map() object. See here -> Map and Set

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

const arrayObject = [
  {id:'a123', bar:'hello'}, 
  {id:'a321', bar: 'foo'},
  {id:'a234', bar: 'more'},
  {id:'a735', bar: 'words'},
  {id:'a167', bar: 'added'},
  {id:'a857', bar: 'now'},
];

var newObj = new Map();

for (var i=0; i<arrayObject.length; i++) {
  const temp = {
        id: arrayObject[i].id,
        bar: arrayObject[i].bar
   };
   newObj.set(arrayObject[i].id, temp);
}

var jsonText = JSON.stringify(Array.from(newObj.entries()));

console.log(jsonText);

// To get at the elements, use .get()

console.log(newObj.get("a321").bar);

<!-- end snippet -->