As the founding member of the npm crew, I'd like to provide some history.
I started using this style originally because I -- not new to JavaScript, and adhering to the "semicolons everywhere" style -- was bitten twice in rapid succession; first by a leading [ causing a function to receive "undefined" as an argument (instead of two arrays), and then again by a leading ( resulting in a non-function being called. Both were unnecessarily difficult to debug, because my brain couldn't see the error. (Even when JSLint complained, I thought it was lying. ,] looks a lot like ], at first glance, and is valid JS. Maybe I'm a little dyslexic or something.)
So, I thought, "New rule: Commas first, prefix ( and [ with semicolons." Problem solved.
But ending a line with a semicolon seemed kind of silly when I was then prefixing with a semicolon the next line, even though I'd learned that it was absolutely necessary for any kind of "safety" (even as an expert, even as a semicolon user). So, I thought, if I'm doing this silly prefixing thing to make ASI safe, why not just let it be safe, and drop them everywhere?
So I did. And it's pretty nice.
I don't understand why people get so upset about how I write programs, especially those that they don't even use or contribute to. The first time a professional JavaScripter cursed me out at the top of his lungs in a bar, literally spitting in my face while he screamed at me, I realized that there was some essential human weirdness involved here, and it became much too interesting to drop. Every time I ask people to please not lie about JavaScript to newcomers, they accuse me of being dogmatic or a semicolon hater.
But I maintain the JavaScript in Node.js as well, which follows Google's (occasionally insane) C++-inspired semicolon-ridden JavaScript style, and I'm fine with that. It's kind of nice, too, in a different way. More dots. Vim's auto-indenter works a little better.
What's wrong with just not lying? I don't get it at all. People who already know C and Java are usually veteran enough to grok weird language warts. People from Python and Ruby have an easier time learning the exceptions than sticking to the rule, since their habits are usually to omit the ceremonial EOL punctuation. And newcomers don't have any preconceptions anyway; they're busy learning why we call "this" a string, and why this is always something different, and crazy shit like "a function is an object and you construct an instance of it with new which calls it on a this that inherits from its prototype". (I mean, seriously, read that sentence to a nonprogrammer, and ask them what it means. It's gibberish!)
But people react to it like I've insulted them personally, when I just ask that they not fill newcomers' heads with lies and fud. I still don't understand it.
I'm having trouble imagining your examples. The first one sounds like you did something like
fn([1,2,]
[3,4])
(but presumably longer) and a comma first would fix that (though so would believing jshint or using a debugger :), but a leading semicolon obviously couldn't be used there. I can't picture the second problem, though, at least not in a way that a trailing semicolon wouldn't have fixed.
On the topic of interaction with other developers, this:
> I don't understand why people get so upset about how I write programs
is unfortunate and is probably the biggest problem in this thread (and the previous one). At this point, I've accepted that some people like comma and semicolon first, and if that's the style of a project I'm contributing to, I'll say "this is really dumb" to myself and then write it in that style anyway. It's correct Javascript, and I think plenty of projects are stupidly designed, or inscrutably written, but at some point you suck it up or go elsewhere. It's just a style.
However, there are some red flags in your post that you should think about if you're interested in some dialogue. This is based just on this one post, and I don't think we've ever actually met, so I don't want to go too far here, but statements like
> I realized that there was some essential human weirdness involved here, and it became much too interesting to drop
> Every time I ask people to please not lie about JavaScript to newcomers
> What's wrong with just not lying? I don't get it at all.
> I just ask that they not fill newcomers' heads with lies and fud. I still don't understand it.
sound like pretty classic trolling for the response you're getting. I'm a firm believer in being precise when explaining topics (especially to newcomers), but there's a difference between trying to correct people that are saying incorrect things and trying to provoke a reaction out of them.
(To his credit, Crockford is actually good about saying "this is valid javascript, but it's a developer anti-pattern" and then explaining why he thinks so. I just disagree with about 25% of his anti-patterns and, of course, he's usually kind of a jerk about them)
I started using this style originally because I -- not new to JavaScript, and adhering to the "semicolons everywhere" style -- was bitten twice in rapid succession; first by a leading [ causing a function to receive "undefined" as an argument (instead of two arrays), and then again by a leading ( resulting in a non-function being called. Both were unnecessarily difficult to debug, because my brain couldn't see the error. (Even when JSLint complained, I thought it was lying. ,] looks a lot like ], at first glance, and is valid JS. Maybe I'm a little dyslexic or something.)
So, I thought, "New rule: Commas first, prefix ( and [ with semicolons." Problem solved.
But ending a line with a semicolon seemed kind of silly when I was then prefixing with a semicolon the next line, even though I'd learned that it was absolutely necessary for any kind of "safety" (even as an expert, even as a semicolon user). So, I thought, if I'm doing this silly prefixing thing to make ASI safe, why not just let it be safe, and drop them everywhere?
So I did. And it's pretty nice.
I don't understand why people get so upset about how I write programs, especially those that they don't even use or contribute to. The first time a professional JavaScripter cursed me out at the top of his lungs in a bar, literally spitting in my face while he screamed at me, I realized that there was some essential human weirdness involved here, and it became much too interesting to drop. Every time I ask people to please not lie about JavaScript to newcomers, they accuse me of being dogmatic or a semicolon hater.
But I maintain the JavaScript in Node.js as well, which follows Google's (occasionally insane) C++-inspired semicolon-ridden JavaScript style, and I'm fine with that. It's kind of nice, too, in a different way. More dots. Vim's auto-indenter works a little better.
What's wrong with just not lying? I don't get it at all. People who already know C and Java are usually veteran enough to grok weird language warts. People from Python and Ruby have an easier time learning the exceptions than sticking to the rule, since their habits are usually to omit the ceremonial EOL punctuation. And newcomers don't have any preconceptions anyway; they're busy learning why we call "this" a string, and why this is always something different, and crazy shit like "a function is an object and you construct an instance of it with new which calls it on a this that inherits from its prototype". (I mean, seriously, read that sentence to a nonprogrammer, and ask them what it means. It's gibberish!)
But people react to it like I've insulted them personally, when I just ask that they not fill newcomers' heads with lies and fud. I still don't understand it.