JavaScript Regex Producing Uncaught SyntaxError: Unexpected token ILLEGAL

Question

I have this in my JavaScript,

alert(words.match(\b.(\w*)\b));

, where words is a string previously defined. But, the regex (\b.(\w*)\b) is producing a console error Uncaught SyntaxError: Unexpected token ILLEGAL. I think it's the backslashes, but no matter what I do, I still get the problem. I have thoroughly researched this problem on Stackoverflow and Google, but none of the results either works or meets my situation.

Here is the regex I am using: http://regexr.com?36u4v. Any held would be greatly appreciated.

Why has my question been voted down?

Mr. Shtuffs
– Mr. Shtuffs

2013-10-27 02:01:57 +00:00
Commented Oct 27, 2013 at 2:01 — Mr. Shtuffs
– Mr. Shtuffs, Commented Oct 27, 2013 at 2:01

Paul S. · Accepted Answer · 2013-10-27 01:55:19Z

4

This comes down to "Is \b.(\w*)\b RegExp ?" Well, kind of, but you haven't told the interpreter that. It is not a RegExp literal in JavaScript. You need to either pass it as a String into the RegExp constructor, or use literal notation, which begins and ends with /

/\b.(\w*)\b/

As for your error, the interpreter reaches the \ first and does not know what this means, so it tells you that the token (\) was unexpected, so is "illegal" where you used it.

For multiple matches, you'll need to set the global flag, for example, to find "foo" multiple times

/foo/g

does this regex work well for selecting all words, excluding spaces and punctuation (other than underscores and hyphens)

\w is shorthand for the class [A-Za-z0-9_], so you're not matching hyphens at the moment. Your . will also match most characters including spaces and punctuation. You can swap the * (zero or more) for a + (one or more) so you don't need the .. Therefore the following may be more suitable for your needs

/\b([A-Za-z0-9_-]+)\b/g

edited Oct 27, 2013 at 1:55

answered Oct 27, 2013 at 1:37

Paul S.

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6 Comments

Mr. Shtuffs Over a year ago

Okay, well that fixes the problem, with a nice explanation. But, now I am faced with another. This regex was supposed to select all words, excluding spaces and punctuation (other than underscores and hyphens), but now it's not doing that. On regexr, it was showing it working well, but now it's not.

Paul S. Over a year ago

Remember that . will match almost anything and that if you want multiple finds, you'll need to set the global flag.

Mr. Shtuffs Over a year ago

Thanks. That seems to fix it.

Mr. Shtuffs Over a year ago

It won't let me accept answer yet. By the way, does this regex work well for selecting all words, excluding spaces and punctuation (other than underscores and hyphens), or is there a better way?

Paul S. Over a year ago

@Mr.Shtuffs please see edit where I explain why, too

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kol · Accepted Answer · 2013-10-27 01:38:10Z

1

You forgot to put your regex literal into slashes:

alert(words.match(/\b.(\w*)\b/));

answered Oct 27, 2013 at 1:38

kol

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