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JavaScript (sh.itjust.works)
submitted 1 week ago by sjmarf@sh.itjust.works to c/programmer_humor@programming.dev
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[-] PoolloverNathan@programming.dev 43 points 1 week ago* (last edited 1 week ago)

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:

[-] victorz@lemmy.world 20 points 1 week ago

So there's yet another level of quirkery to this bullshit then, it seems. ๐Ÿ˜† Nice digging! ๐Ÿค

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

> eval('{} + []')
0
> eval('({}) + []')
'[object Object]'
[-] PoolloverNathan@programming.dev 10 points 1 week ago

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

[-] dejected_warp_core@lemmy.world 3 points 1 week ago

/me goes back to get second folding chair.

[-] victorz@lemmy.world 1 points 1 week ago* (last edited 1 week 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.

this post was submitted on 23 Jun 2024
724 points (96.4% liked)

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