Avoid instanceof (for cross-realm support)

[vweevers]

Rewrite value instanceof ArrayBuffer etc.

[vweevers]

Only one left actually:

level-js/index.js

Line 128 in 3a8b861

} else if ((typeof key === 'number' || key instanceof Date) && !isNaN(key)) {

The other one doesn't matter because it's only used on values coming out the IndexedDB:

level-js/util/mixed-to-buffer.js

Line 6 in 3a8b861

if (value instanceof Uint8Array) return toBuffer(value)

[ralphtheninja]

What do you mean by cross-realm support and why is instanceof problematic?

[vweevers]

See https://jakearchibald.com/2017/arrays-symbols-realms/#multiple-realms

[vweevers]

Also https://github.com/jasnell/proposal-istypes

[vweevers]

And https://github.com/ljharb?utf8=%E2%9C%93&tab=repositories&q=is-&type=&language=

[ralphtheninja]

So, yeah, feeling pretty hipster right now.

😆

[ralphtheninja]

@vweevers Are there any rules on when it is important and not important, e.g. why isn't instanceof in the constructor and the Uint8Array important?

[vweevers]

It depends on the likelihood that the value was created in a different realm. For keys and values coming straight out of IndexedDB it doesn't matter - as we know they come from the current realm (where IndexedDB and the structured clone algorithm lives).

It pretty much only matters for user input. When a user does db.get(date), that date key might have come from a different realm.