Using a dictionary instead of an object?

The following easily fails:

const tlru = require('tiny-lru');
const cache = tlru();
cache.get('toString');

and this is a common issue when objects, instead of dictionaries, are used in conjunction of the in operator.

In NodeJS, they’ve benchmarked that the best way to go is:

function Dict() {}
Dict.prototype = Object.create(null);

Once you have that, instead of this.items = {}; you’d go this.items = new Dict; and you grant no name clashing through the prototype could possibly ever happen.

Thoughts?

[WebReflection]

Just to be clear:

• using an object literal as trash bin has never been a good idea in general, that is why Map was introduced in the language
• assuming you can be careless and use the object literal, you should not use the in operator, because it reveals prototype chain details
• even using items.hasOwnProperty would be a bad choice, 'cause hasOwnProperty could be used as cache, so that having hasOwnProperty.call(items, key) would be at least safer
• because of all these gotchas described in previous points, they introduced Object.create(null) to exactly address all these common hidden caveats with objects literals (and thanks gosh it works on prototype too)
• as result, you are using the wrong primitive to obtain unsafe, easy to break, results

I’ve been working and contributing in Open Source for 20 years, and just landing PRs is not usually welcome, because devs might have reasons to pick one approach instead of another.

And yet, you are blaming me for opening a bug and discussing a possible solution before opening a PR … so yes, you’ve been a dick (since you mentioned that part).

Best Regards.

[avoidwork]

I’m also gonna lock this; anyone can open a pr if they want to land a change.