JavaScript

Sjmarf@sh.itjust.works to Programmer Humor@programming.dev – 709 points –
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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:

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]'

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

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.