I've seen a few reasons. The main ones I encounter are: raising the skill requirement to contribute (you have to know JS better than average to never use a semicolon, and do so correctly), aesthetic (fewer characters looks better), and minimalism (don't use what you don't need).
That's insane. Good programmers need not know stupid tiny nits about Javascript (heck, I've worked on a Javascript JIT and I don't really know Javascript). That does not mean that they are not skilled.
> aesthetic
I don't understand how "you must carefully understand how the language parses to understand this line of code" is aesthetically pleasing when compared to unambiguity.
> minimalism
Here, it is needed, at least arguably (by douglascrawford). You could argue that the "optional semicolons" rule is ugly and not minimalistic, and thus the minimalistic approach would be to not use that rule.
Sure the "raising the skill level" bit is just trolling. Omitting semi-colons is about removing ambiguity, and making it easier to spot inconsistencies. As a bonus, code looks cleaner.
In this case, the minifier is breaking the code, regardless.
Can you parse this expression without parentheses?
a && b && c || d || e + f > g && h
The parser sure can. Do you have all the operator precedences memorized, or do you use superfluous parentheses because you're not always sure?
It's true that the semicolon is not needed, and it's true that the minifier is breaking code. It may even be true that Crockford should fix it. But that doesn't change the fact that the omit-the-semicolons position is absurdly immature hipster posturing that serves no engineering purpose.
Do you use parenthesis to denote order of operations in all cases, even when extremely obvious? If not, should we assume your position is absurdly immature hipster posturing that serves no engineering purpose?
I'm sure there is a whole huge debate here that I'm unaware of, but it seems like a largely aesthetic choice to me, and on that basis, I find it really jarring as someone who is not an everyday JS author.
Same reason people don't use semi-colons in Python, I imagine.
Besides, I'm not willing to acknowledge any reasons for using semi-colons as significant. And without any significant reasons for it, I may as well not use them. Besides, it makes the code prettier :).
I always think of using semicolons like using parentheses when doing math in code. It makes the order of operations explicit rather than implied. For example,
1 + 2 * 3
Solves to 7, obviously. But I'll write it in code like this:
1 + (2 * 3)
Just to make it clear that I know what I mean, and I mean do the operations in _this_ order.
Similarly, using semicolons to end lines means I am saying loud and clear... this line of code ends HERE.
Amusingly, I agree with your premise but not really your conclusion. Adding a semi-colon is like adding parentheses. But I think redundant parentheses add visual clutter--unless I have a very complicated expression, I leave them off. (Maybe it's the Haskell code style rubbing off on me...)
So I actually think that 1 + 2 * 3 is better than 1 + (2 * 3). I usually find reading a line with less stuff easier, so I prefer the shorter between two equivalent expression.
Besides, adding a semi-colon is more like surrounding the whole expression with parentheses rather than just grouping. And you would never write (1 + (2 * 3)). And yet that also says, loud and clear, the same thing!
I've used some languages with optional semi-colons--Python and Haskell, for example. I've never thought that missing them made the code less readable--it's always been the opposite. Going back to Java and having to use semi-colons everywhere becomes increasing annoying as I grow more acclimated to languages without.
In short, I see where you're coming from but don't really agree.
Is it obvious that there is a missing semi-colon at the end of line 1? The code is technically correct without it (not that I approve of it). You can assume it's wrong, but it's just a guess.
If your code is in no-semi-colon style, there is no ambiguity, you can be 100% sure that this is a mistake: there always should be a semi-colon guarding that parenthesis, regardless of intent:
var value = x + fn
;(y).burp()
It's about removing ambiguity and visual clutter with a simple set of rules.
How many JS programmers know the difference between a function expression or declaration, and the semi-colon that should follow or not? You're dependent on a linter. Following the no-semi-colon rules makes your intentions clear in every case, without machine validation.
I don't follow this argument. Putting a semicolon at the end of every statement, regardless of what follows, seems to be an even easier way to avoid making this bug.
I think the usual semi-colon-less style is to put a semi-colon in front of lines beginning with parentheses (and only those lines). This is the one potential problem area if you don't have semi-colons everywhere, so you can avoid almost all (or maybe actually all) problems just by prepending a semi-colon to those lines.
I think Ricardo's point is that this style (having a semi-colon only before parentheses at the beginning of the line) makes your intentions more explicit.
> Putting a semicolon at the end of every statement
Sounds like a viable strategy - but you have to parse where every statement ends in your head. The situations where you don't end a line with a semi-colon are more numerous than the rules you need to write semi-colon-free code. Besides, if it's so simple, why not leave it to the interpreter?
It's trivial to parse when statements end in my head, because I write code in a structure that makes it unbelievably clear where statements begin and end (with or without semicolons.) Knowing that is of prime importance to human readability, so it has to be dead obvious or the code sucks.
I'd love to leave it to the interpreter, but the interpreter doesn't put a semicolon at the end of every statement for me, as I write them naturally. It puts a semicolon at the end of... most statements.
This is a silly example because it's so simple. E.g. You can just write 2*3+1, which is easier to read. Regardless, I'd wonder why you put the parenthesis there, as if it were some odd hack or workaround for some obscure bug.
