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I have a regular expression testing for numbers(0-9) and/or forward slashes (/). It looks like this:

/^[0-9/]+$/i.test(value)

Now I believe this to be correct, but the eclipse javascript validator disagrees:

Syntax error on token "]", delete this token

I suppose this is because the separator/delimiter is / and eclipse 'thinks' the regex is finished (and therefore a ] would be unexpected).

We can satisfy eclipse by escaping the / like so:

/^[0-9\/]+$/i.test(value)

Note that both versions work for me.

My problem with this is:

  • As far as I know I do not need to escape the forward slash specifically in that range. It might be situation specific (as in, for javascript it is the used delimiter).
  • Although they both appear to be working, I'd rather use the 'correct' version because of behaviour in different environments, and, well.. because correct and all :)

Does anyone know what I'm supposed to do? Escape or not? I did not find any reputable site that told me to escape the / in a range, but the Eclipse-validator is probably not completely stupid...

thefourtheye
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Nanne
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1 Answers1

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The standard clearly says you can put anything unescaped in a character class except \, ] and newline:

RegularExpressionClassChar ::
   RegularExpressionNonTerminator but not ] or \
   RegularExpressionBackslashSequence

RegularExpressionNonTerminator ::
    SourceCharacter but not LineTerminator

( http://es5.github.com/#x7.8.5 ). No need to escape /.

On the other side, I personally would escape everything when in doubt, just to make less smart parsers happy.

georg
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  • Nice one :). I'm not really up-to-speed with the " Ecma Standard", this is the standard used for most .js parsers? And can you escape something that doesn't need to be escaped without breaking stuff? – Nanne Feb 10 '12 at 11:29
  • @Nanne: yes, most javascript vendors try to keep up with the ecma standard. Not everyone gets it right completely, but basic things should work the same everywhere. And yes, an extra backslash doesn't hurt, even when it's safe to omit it. – georg Feb 10 '12 at 11:37