How to Correctly Use the Alternation Operator within Square Brackets in JavaScript Regex?

Incorrect Regex Syntax: Alternation Operator within Square Brackets

While constructing a JavaScript regex to match search queries in a string, it's crucial to pay attention to regex syntax. One common issue is the incorrect usage of the alternation operator (|).

Issue:

The provided regex,

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

aims to match strings containing 'word' or 'qw' in addition to 'wd'. However, attempting to use the alternation operator within square brackets, as in [wd|word|qw], leads to incorrect matching.

Solution:

To rectify this issue, the square brackets should be replaced with parentheses. Parentheses in regex denote logical groupings, allowing alternation within the group. The correct regex should be:

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

Alternatively, the non-capturing group syntax, denoted by (?:wd|word|qw), can also be used. This ensures that the alternation group is not captured as a separate match.

The above is the detailed content of How to Correctly Use the Alternation Operator within Square Brackets in JavaScript Regex?. For more information, please follow other related articles on the PHP Chinese website!