javascript - Alternation operator inside square brackets does not work - Stack Overflow

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I'm creating a javascript regex to match queries in a search engine string. I am having a problem with alternation. I have the following regex:

.*baidu.*[/?].*wd{1}=

I want to be able to match strings that have the string 'word' or 'qw' in addition to 'wd', but everything I try is unsuccessful. I thought I would be able to do something like the following:

.*baidu.*[/?].*[wd|word|qw]{1}=

but it does not seem to work.

I'm creating a javascript regex to match queries in a search engine string. I am having a problem with alternation. I have the following regex:

.*baidu..*[/?].*wd{1}=

I want to be able to match strings that have the string 'word' or 'qw' in addition to 'wd', but everything I try is unsuccessful. I thought I would be able to do something like the following:

.*baidu..*[/?].*[wd|word|qw]{1}=

but it does not seem to work.

• javascript
• regex

Share Improve this question Follow edited Apr 14, 2018 at 9:58 Wiktor Stribiżew 628k4141 gold badges498498 silver badges614614 bronze badges asked Apr 4, 2012 at 22:03 well actuallywell actually 12.4k2121 gold badges5555 silver badges7070 bronze badges 2

• 1 [] creates a character class, use (wd|word|qw) instead. Also get rid of that {1}, it's useless. – NullUserException Commented Apr 4, 2012 at 22:04
• A little more context on what you are trying to acplish would help us to help you a lot more :D – Code Jockey Commented Apr 4, 2012 at 22:26

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2 Answers 2

Sorted by: Reset to default 7

replace [wd|word|qw] with (wd|word|qw) or (?:wd|word|qw).

[] denotes character sets, () denotes logical groupings.

Your expression:

.*baidu..*[/?].*[wd|word|qw]{1}=

does need a few changes, including [wd|word|qw] to (wd|word|qw) and getting rid of the redundant {1}, like so:

.*baidu..*[/?].*(wd|word|qw)=

But you also need to understand that the first part of your expression (.*baidu..*[/?].*) will match baidu. hello what spelling/handle????????? or hbaidu-/ or even something like lkas----jhdf lkja$@@!3hdsfbaiduglaksjhdf.[($?lakshf, because the dot (.) matches any character except newlines... to match a literal dot, you have to escape it with a backslash (like \.)

There are several approaches you could take to match things in a URL, but we could help you more if you tell us what you are trying to do or acplish - perhaps regex is not the best solution or (EDIT) only part of the best solution?

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