Micro-post:
I was truly shocked to find today that in JavaScript regular expressions, . (the decimal point) doesn't do what I thought it did. I thought . meant "match any character." You too? Yeah. But it doesn't. Specifically, . doesn't match line terminators (so, \r, \n, \u2028, and \u2029). From Section 15.10.2.8:
The productionAtom :: .evaluates as follows:
- Let A be the set of all characters except LineTerminator.
- Call CharacterSetMatcher(A, false) and return its
Matcherresult.
...which if you spend really quite a long time looking tells you that . matches anything but line terminators.
Maybe I'm just parading my ignorance here, but I would have thought that absent the "multiline" flag or something, . matched everything. Nope. If you want to do that, use [\s\S] (e.g., everything that either is or isn't whitespace).
Happy coding!
3 comments:
I won't pretend I knew but I with my experience of PHP/PCRE, I would have suspected that new lines could be treated differently.
And there's more:
http://php.net/manual/en/reference.pcre.pattern.modifiers.php
I wonder if for example, the PCRE_MULTILINE switch isn't another potential trap in JavaScript regular expressions. I'm mixing PHP and JS but you get the point, right.
That's what I meant about "absent the 'multiline' flag or something" (JavaScript's multiline flag is pretty much like PHP's and Perl's).
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