[dvh]

I love how he omitted semicolons so that it cannot be used as bookmarklet.

[ylyn]

Just minify it...?

[slimed]

Imagine still using semi-colons in JS source in 2020 and "bookmarklet compatibility" being your reasoning.

[jarfil]

Semicolons in JS is how you differentiate between someone who understands that code ambiguity leads to pain, vs someone who shouldn't be allowed near multi-line statements.

[pretty_lorelei]

Honest question: how often does the code ambiguity due to lack of semicolons lead to non-obvious bugs? I'm nowhere close to being a JS expert, but I've done some JavaScript-heavy pet projects and I've got an ambiguous statement interpreted wrong exactly once, and the cause was pretty obvious within a minute of looking at the error.

[fenomas]

In my experience, precisely as often as you write statements that start with a left bracket or paren. E.g.

    [1, 2, 3].forEach( ... )
    (function(){ ... })()

Statements like that are virtually always errors under ASI, but if you avoid them nothing else causes problems.

[DonHopkins]

It's not so much how often it happens, but how freaking hard it is to find the problem by inspection when it does happen.

[fenomas]

Linters correctly highlight all the ASI-related that realistically happen. (Or eslint does anyway, can't speak for others.)

[z3t4]

If you accidently write a comma instead of semicolon it can have interesting effects.

[slimed]

Please give a concrete example of this pain that you have actually experienced. I understand that ASI (automatic semi-colon insertion) is in theory ambiguous because you are relying on the compiler, or in some cases many different compilers, to execute the statement correctly. In practice, for over a decade, I have never run into such an issue. I suspect it's due to engineers trying to get too cute with their implementations.

[DonHopkins]

Crockford on Bootstrap's semicolon omission: “insanely stupid code” (github.com)

https://news.ycombinator.com/item?id=3842713

https://github.com/twbs/bootstrap/issues/3057

And don't forget to semicolon-harden your most important mission-critical code:

https://www.bluejava.com/4PN/Semicolons-in-JavaScript---The-...

    ;;;;;;;;;;;; // protective wall of semicolons
    ;;var a = 10, b = 20;;
    ;;
    ;;function add(a,b)
    ;;{;;
        ;;return a + b;;;;;;;; // this function MUST work
    ;;};;
    ;;;;;;;;;;;; // protective wall of semicolons

[Etheryte]

Without opening your console, consider whether the below code throws or not and why:

  var a = []
  var b = ''
  var c = {}
  [].concat.apply(a, [b, c])

[hombre_fatal]

;[]... is one of two rules you memorize when you omit semis. It's not even that common of a case, though your own example doesn't even make sense.

I don't really understand the drama, just like people who use semis in place you don't need them. In real code, you should be using a linter anyways. At which point semis or no semis becomes purely an aesthetic concern. Like whether you use single or double quotes.

I haven't used semicolons in over 8 years and never had an issue. And with tools like eslint and prettier, you have no excuse to be making such trivial mistakes, like adding superfluous semicolons like function(){};

[gherkinnn]

A typical response is

  return

  false

Where the program returns undefined. I can only think of these examples as straw men. Not once did I run in to an ASI bug.

[fenomas]

Note though, that this ambiguity doesn't really affect the whole "whether to use semicolons" debate either way. If anything, it's more likely to occur in code that does use semicolons than in code that doesn't.

[slimed]

Thank you. I have yet to see an example in this thread or anywhere else that did not fall into this category.

[z3t4]

    foo=arr[i]


    (counter++)

[z3t4]

    if(foo)
      doX()
      doY()

[NoInputSignal]

Intuitively this becomes:

if(foo) doX() doY();

Intuitively, as a someone who uses C style languages, this becomes:

if(foo) doX(); doY();

Can someone confirm which intuition is correct?

I ask because, to me: it not being intuitive is a problem--even if it is not classified as ambiguous.

It being only contextually intuitive, also seems somewhat problematic--but maybe excusable if it is assumed you know some similar language going into it and it behaves similarly to that other language.

[slimed]

For the benefit of the rest of us, can you explain what issues this causes and where/how you are running this code?

[wwweston]

Bookmarklets are situationally pretty useful; they’re the easy entry to custom cross-site userscripting, a test drive before going full extension. They’re as legit a use of JS as anything else is.

(That said: if you use someone else’s code, putting up with their style is part of the bargain, even if I think leaving out semicolons is pointless aesthetic bikeshedding.)

[hombre_fatal]

> even if I think leaving out semicolons is pointless aesthetic bikeshedding

Bikeshedding isn't when you paint the bikeshed your favorite color, it's the bickering over the shade it should be painted which is actually what you did, especially since the damage has already been done. ;)

This whole thread is insufferable bikeshedding.

[detaro]

Imagine not understanding why bookmarklet compatibility is cool for something like this and putting people down for it with a cheap "it's 2020" meme.

[slimed]

A bash one-liner solves this problem for you. If you think it's "cool" to execute JS as a bookmarklet you are free to distribute your own version of the library. The original commenter was the one "putting people down" by demanding the author do it "the right way".

[lucideer]

upvoted, because yes!

but also, violentmonkey