Monday 10 June 2019

Regex - Match attribute in a HTML code





I have problem with matching the html attributes (in a various html tags) with regex. To do so, I use the pattern:



myAttr=\"([^']*)\"


HTML snippet:







it selects text from the myAttr the end /> but I need to select the myAttr="..." ("http://example.com")


Answer



You have an apostrophe (') inside your character class but you wanted a quote (").



myAttr=\"([^"]*)\"


That said, you really shouldn't be parsing HTML with regexes. (Sorry to link to that answer again. There are other answers to that question that are more of the "if you know what you are doing..." variety. But it is good to be aware of.)



Note that even if you limit your regexing to just attributes you have a lot to consider:





  • Be careful not to match inside of comments.

  • Be careful not to match inside of CDATA sections.

  • What if attributes are bracketed with single quotes instead of double quotes?

  • What if attributes have no quotes at all?



This is why pre-built, serious parsers are generally called for.


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