Javascript and semicolon insertion

http://inimino.org/~inimino/blog/javascript_semicolons

by mnemonik • 16 years ago

27 12 16 years ago

orangecat• 16 years ago

A horrible Javascript misfeature, second only to default global scope. I always use semicolons, but as the article notes even if you do that you still have to be aware of how automatic insertion works.

notauser• 16 years ago

From the article, the only really nasty things are:

  [a].forEach(fn(){})
  [b].forEach(fn(){})
  // Parses as [a][b]

  return
  a+b
  // Parses as return;

You would have to work pretty hard to trigger the rest.

I'm curious about the speed trade offs from removing semicolons. You shrink the source code a little, but does the parser throwing exceptions all the time bump up execution time?

barrkel• 16 years ago

A parser would not normally handle this kind of thing with exceptions, and any cost would only be paid once, at parse time when building a syntax tree, not at execution time. Very few languages interpret text directly, rather than interpreting trees, as the trees are far easier to work with, more efficient, etc.

mkramlich• 16 years ago

this issue and the 'var' keyword are two of the reasons I feel Python is mostly a superior language. (Not necessarily completely, just overall.)

pdx• 16 years ago

Every since I started using JSMin, I've needed to add semicolons after all my functions, which is something that I can't seem to remember to do as a habit.

cmelbye• 16 years ago

Frames? Is it the 90s again?

inimino2• 16 years ago

No, there are no frames.

mdaniel• 16 years ago

I realize this is not the forum for this, but hopefully it will serve as a warning to others: the linked article does not scroll on the iPhone (horiz or vert orientation).

"Cool" layouts are all fun and games, but usability is king.

noblethrasher• 16 years ago

It does but you have to use two fingers.

frofro• 16 years ago

Yup, I only learned about this feature a few months ago. It also makes other apps like the standard Google Reader usable.

inimino2• 16 years ago

It seems to be an issue with the iPhone and iPad. Hopefully Apple will fix it, as I'm sure there are other sites with scrollable areas within a page.

If not, I'll probably find a workaround eventually.

tszming• 16 years ago

Use JSLint: http://www.jslint.com

Javascript and semicolon insertion

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