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0 pointsslimed6y ago0 comments

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

0 comments

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_lorelei6y ago

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.

fenomas6y ago

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.

DonHopkins6y ago

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.

1 more reply

z3t46y ago

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

slimedOP6y ago

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.

DonHopkins6y ago

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

Etheryte6y ago

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])

1 more reply

gherkinnn6y ago

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.

2 more replies

z3t46y ago

    foo=arr[i]


    (counter++)

z3t46y ago

    if(foo)
      doX()
      doY()

2 more replies

wwweston6y ago

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_fatal6y ago

> 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.

detaro6y ago

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.

slimedOP6y ago

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".

j / k navigate · click thread line to collapse

0 comments

jarfil6y ago

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_lorelei6y ago

fenomas6y ago

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.

DonHopkins6y ago

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.

1 more reply

z3t46y ago

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

slimedOP6y ago

DonHopkins6y ago

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

Etheryte6y ago

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])

1 more reply

gherkinnn6y ago

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.

2 more replies

z3t46y ago

    foo=arr[i]


    (counter++)

z3t46y ago

    if(foo)
      doX()
      doY()

2 more replies

wwweston6y ago

(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_fatal6y ago

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

This whole thread is insufferable bikeshedding.

detaro6y ago

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.

slimedOP6y ago

j / k navigate · click thread line to collapse