3 ms·

Seems he took the Wat talk a little personally, but I'm not sure why he defends {} + [] by saying the first { is a statement... wat?

• _mhr_ 13y ago
  It's automating semicolon insertion. The browser translates {} + [] into {}; + [], so + [] === 0 too. {}; is undefined.
  • codeflo 13y ago
    Being pedantic: it's NOT semicolon insertion. Your actual point is correct, the {} is an empty block statement, and the +[] is a separate expression statement. It's equivalent to "{} 0". However, semicolon insertion is only triggered when there's a newline at a position where there would otherwise be a syntax error. Here, neither is the case: blocks don't have to be terminated by semicolon (so no syntax error), and there's no newline in the source code!
• drostie 13y ago
  It's because they wanted to say both: if (a) b; and if (a) { b; c; } which tends to make you think of curly braces as a syntactic feature which can appear anywhere, turning many lines of code into one line of code. If you think that way then these should possibly also be valid: {b; c} {b} {} but, since JS scope is function-oriented and in other places (e.g. functions) the braces are ultimately needed anyways, even for one-liners, it seems like this was a stupid choice and we should have just rejected the form: if (a) b; and then the reuse of {} for lightweight (if non-robust) hashmaps would perhaps be unambiguous again.
  • kbenson 13y ago
    Which is exactly what Perl did, but to alleviate the clumsiness of single statement if conditionals they added a post-conditional if statement of the form STATEMENT if CONDITION; (which has the benefit of being how some people express simple conditionals in real life. "Go left if you see the blue house.")