正则表达式排除HTML标记中包含的匹配项

Question

I'm trying to create a Regex expression to match content within a HTML document, but I wish to exclude matches contained within a tag itself. Consider the following:

<p>Here is some sample text for my widgets</p>
<a href="http://mywidgets.nowhere">Click here to view my widgets</a>

I would like to match 'widgets' so that I can replace it with a different string, say 'green box', without replacing the match within the url.

Matching 'widgets' is, well, easy as anything, but I'm struggling to add the exclude to check for 'widgets' when it appears within the opening and closing tag '<>'.

My current workings: As a first step I have started to match 'widgets' contained within '<>'. (I can then move on to make this an exclude later) However the below string seems to match the whole document, even though I have placed an exclude on the closing > to make sure widgets appears within a tag.

<.*[^>]widgets.*[^<]>+ 

It's probably down to lazy / greedy, but I can't quite work it out!

Answer 1

Overview

By no means is this a great answer since it's parsing HTML with regex, but it does work for the test case given by the OP.

See RegEx match open tags except XHTML self-contained tags for more information.

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Code

See regex in use here

(?<!<[^>]*)widgets

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Explanation

• (?<!<[^>]*) Negative lookbehind ensuring what precedes is not < followed by any character except > (any number of times)
• widgets Match this literally

Answer 2

This may partially work:

(?:^|>)[^<]*widgets

This will start looking from the start of a line (if the /m flag is used) or the end of a tag (so we know we are not in one), and advance as many characters possible that are not <, meaning you can't open another tag, before looking for widgets. The issues with this are that it may give weird results if you have a > inside a tag (eg, in javascript), or if a single tag can span over multiple lines and it won't find several instances of "widgets" in the same substring. To solve those issue, you'd better use an actual XML parser as advised by ctwheels