StrMap backing object inherits from Object.prototype and lookup uses in

Question

StrMap backing object inherits from Object.prototype and lookup uses in

Closed this issue 10 years ago · 6 comments

I imagine lookup will think that keys like "toString" and "hasOwnProperty" exist in the object, even though the functions that rely on Object.keys or iteration through for-in won't see these properties because they're non-enumerable. I haven't tested this, but I'm pretty sure I'm right just by looking at the implementation.

michaelficarra commented 10 years ago

Yep.

Answer 1 · 2015-07-01T14:31:14.000Z

Yeah, I'm pretty sure you're right too.

Answer 2 · 2015-07-01T15:04:54.000Z

There's two possible solutions:

use a hasOwnProperty test instead of in
use Object.create(null) as the backing object

I'd probably decide which to do based on performance. I'm going to guess the first option is better optimised in most implementations right now, but tests should be done to confirm.

Answer 3 · 2015-07-01T15:07:07.000Z

Interesting, I wasn't aware of option 2 - I just assumed we'd have to use hasOwnProperty. You get a truly empty prototype with Object.create(null) then?

Answer 4 · 2015-07-29T05:08:05.000Z

@garyb is this fixed now after cca72e0#diff-f398949aafcfd55358d80eec690ee116?

Answer 5 · 2015-07-29T10:42:50.000Z

Yes! (Although it also broke it, #39 fixed the new bug though) Thanks for the reminder.