Hi !

Given the following sample items :

I can store these in an array :

const data = [
  { id: 'xvZwiCpi', firstName: 'Frederic', age: 42 },
  { id: 'Nzd9UsGT', firstName: 'Naomi', age: 24 },
  { id: 'QiDXP2wA', firstName: 'Thea', age: 53 },
  { id: 'JpYeAY7H', firstName: 'Mathew', age: 35 }
];

Thus access them the same way by ID :

console.log(data.find(item => item.id === 'xvZwiCpi'));

And by properties :

console.log(data.find(item => item.firstName === 'Frederic').id);

Or I can store these in an object :

const data = {
  'xvZwiCpi': { firstName: 'Frederic', age: 42 },
  'Nzd9UsGT': { firstName: 'Naomi', age: 24 },
  'QiDXP2wA': { firstName: 'Thea', age: 53 },
  'JpYeAY7H': { firstName: 'Mathew', age: 35 }
};

Thus more easily access properties by ID :

console.log(data['xvZwiCpi'].firstName);

But more hardly access ID by properties :

console.log(Object.entries(data).find(([id, item]) => item.firstName = 'Frederic')[0]);

I could duplicate IDs :

const data = {
  'xvZwiCpi': { id: 'xvZwiCpi', firstName: 'Frederic', age: 42 },
  'Nzd9UsGT': { id: 'Nzd9UsGT', firstName: 'Naomi', age: 24 },
  'QiDXP2wA': { id: 'QiDXP2wA', firstName: 'Thea', age: 53 },
  'JpYeAY7H': { id: 'JpYeAY7H', firstName: 'Mathew', age: 35 }
};

To slightly simplify that previous line :

console.log(Object.values(data).find(item => item.firstName = 'Frederic').id);

But what if a single variable type could allow doing both operations easily ?

console.log(data['xvZwiCpi'].firstName);
console.log(data.find(item => item.firstName === 'Frederic').id);

Does that exist ?

If not, I’m thinking about implementing it that way :

const data = new Proxy([
  { id: 'xvZwiCpi', firstName: 'Frederic', age: 42 },
  { id: 'Nzd9UsGT', firstName: 'Naomi', age: 24 },
  { id: 'QiDXP2wA', firstName: 'Thea', age: 53 },
  { id: 'JpYeAY7H', firstName: 'Mathew', age: 35 }
], {
    get: (array, property) =>
        array[property]
        ||
        array.find(item => item.id === property)
});

In which case I’d put it in a lib, but how would this be named ?

I’d also make a second implementation that would enforce ID uniqueness and use Map to map IDs with indexes instead of running find : while the first implementation would be fine for static data, the second one would be more suitable for dynamic data.

Would this make sense ?

Thanks