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JavaScript (sh.itjust.works)

submitted 4 months ago by [email protected] to c/[email protected]

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[–] [email protected] 43 points 4 months ago* (last edited 4 months ago) (1 children)

The inspector REPL evaluates as a statement-with-value (like eval), so the {} at the beginning is considered an empty block, not an object. This leaves +[], which is 0. I don't know what would make Node differ, however.

Edit: Tested it myself. It seems Node prefers evaluating this as an expression when it can, but explicitly using eval gives the inspector behavior:

[–] [email protected] 20 points 4 months ago (1 children)

So there's yet another level of quirkery to this bullshit then, it seems. 😆 Nice digging! 🤝

I also noticed that if you surround the curlies with parentheses, you get the same again:

> eval('{} + []')
0
> eval('({}) + []')
'[object Object]'

[–] [email protected] 9 points 4 months ago (2 children)

Yep, parentheses force {} to be interpreted as an expression rather than a block — same reason why IIFEs have !function instead of just function.

[–] [email protected] 3 points 4 months ago

/me goes back to get second folding chair.

[–] [email protected] 1 points 4 months ago* (last edited 4 months ago)

I thought IIFE's usually looked like (function (...params) {})(...args). That's not the latest way? To be honest I never used them much, at least not after arrow functions arrived.