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I see the bug as JSLint's problem, not the code in question (though admittedly that was bad code). I agree that if your tooling requires semicolons you should b

I see the bug as JSLint's problem, not the code in question (though admittedly that was bad code). I agree that if your tooling requires semicolons you should be pragmatic and include them, but the reality is that parsers/minifiers are mostly built with the assumption that users won't always include semicolons, so that's a largely hypothetical situation. I definitely agree that you should code defensively, but I'm just not seeing why adding semicolons where ASI kicks in is a practical thing to do. I don't agree semicolons make the code more readable, but if there was such a case you should definitely add them. And everyone - not just people who omit non-ASI'ed semicolons - will forget to include them where needed eventually, but that's not even an especially painful bug. There are in my opinion more dangerous style choices that are ignored, like daisy-chained declarations. Writing var x = 1, y = 2, z = 3 is a pretty lousy idea, as it unnecessarily couples the meaning of several lines of code together, and makes code harder to edit. If you unthinkingly truncate the first line you get y = 2, z = 3 a pair of global assignments! That could be a really pernicious bug if you have supposedly 'local' variables sharing the name with an existing global object. It's better to be defensive and write var x = 1 var y = 2 var z = 3 if only for editability. My point is that the strong feeling on 'Semicolons' vs 'No Semicolons' is largely a product of focusing bias (http://en.wikipedia.org/wiki/Anchoring); http://en.wikipedia.org/wiki/Anchoring); to the extent that it is a problem either way it is a minor one, evidenced by the fact that similar stylistic dangers (see above) are either unfairly ignored or rightly not fretted over. tl;dr I don't see a practically valuable reason to use them where ASI does the work for you, semicolon vs semicolon is barely a practical issue either way.

wallyhs 12y ago
I am - I think - looking at this from a safe-by-default perspective. Everyone will forget to include a semicolon eventually as you pointed out, but shouldn't your default strategy be the safest one? Maybe I am missing something. There are obviously cases where missing semicolons do cause problems. Is there a situation in which adding a semicolon where allowed causes problems or increases the chances of introducing a bug in the future?
- BrendanEich 12y ago
  What's the default, though? If I try adding semicolons and over-do it, probably I'm ok. But I might make an empty statement while loop body -- an iloop. And being human, I will inevitably leave a crucial semicolon out. I agree with the parent post. You can go wrong with either C-like or "NPM house" style. Linters are important, moreso in JS than in modern C and C++ (back to the future; I remember old C, which was wildly permissive). Pick your poison, study it well and dose carefully.
  - wallyhs 12y ago
    Now I know where my bias comes from: I did not consider going wrong with semicolons in C. Perhaps that is because C is my oldest friend. You are of course correct that the C style is not perfect either. Thanks for the reply.

wallyhs 12y ago

I am - I think - looking at this from a safe-by-default perspective. Everyone will forget to include a semicolon eventually as you pointed out, but shouldn't your default strategy be the safest one? Maybe I am missing something. There are obviously cases where missing semicolons do cause problems. Is there a situation in which adding a semicolon where allowed causes problems or increases the chances of introducing a bug in the future?

BrendanEich 12y ago
What's the default, though? If I try adding semicolons and over-do it, probably I'm ok. But I might make an empty statement while loop body -- an iloop. And being human, I will inevitably leave a crucial semicolon out. I agree with the parent post. You can go wrong with either C-like or "NPM house" style. Linters are important, moreso in JS than in modern C and C++ (back to the future; I remember old C, which was wildly permissive). Pick your poison, study it well and dose carefully.
- wallyhs 12y ago
  Now I know where my bias comes from: I did not consider going wrong with semicolons in C. Perhaps that is because C is my oldest friend. You are of course correct that the C style is not perfect either. Thanks for the reply.