object-cull

Create a copy of an object, based on which properties were accessed.

import { prepare, apply } from 'object-cull';

const proxy = prepare({
    firstname: 'Terrell',
    lastname: 'Snider',
    friends: [
        { firstname: 'Rachelle', lastname: 'Knight' },
        { firstname: 'Ila', lastname: 'Farrell' },
        { firstname: 'Vasquez', lastname: 'Flynn' }
    ],
    pets: [
        { name: 'Bobo', species: 'Great Dane' }
    ]
});
console.log(proxy.firstname); // Terrell
console.log(proxy.friends[0].firstname); // Rachelle
const { kept, culled } = apply(proxy);
console.log(kept);
/*
{ firstname: 'Terrell', friends: [ { firstname: 'Rachelle' } ] }
*/
console.log(culled);
/*
[
    { path: 'lastname', value: 'Snider' },
    { path: 'friends.0.lastname', value: 'Knight' },
    { path: 'friends.1', value: { firstname: 'Ila', lastname: 'Farrell' } },
    { path: 'friends.2', value: { firstname: 'Vasquez', lastname: 'Flynn' } },
    { path: 'pets', value: [ { name: 'Bobo', species: 'Great Dane' } ] }
]
*/
const unused_bytes = culled.reduce((total, item) => {
    return total + JSON.stringify(item.value).length;
}, 0);
const percent_unused = 100 * unused_bytes / JSON.stringify(proxy).length;
console.log(${percent_unused}% of the data was unused);

Why?

Mostly for server-side rendering. You might not need to serialize all your data to send it to the client.

Prior art

• js-off

License

MIT