RegExp - Replace all matches between two substrings

Question

Is it possible to replace all matches between two sub strings in one regular expression?

My case is that I want to inject HTML after the li tag but only inside myList.

Before:

<ul class="myList">
    <li>List item</li>
    <li>List item</li>
</ul>

After (... would be the injected markup):

<ul class="myList">
    <li>...List item</li>
    <li>...List item</li>
</ul>

Any help would be great, thanks.

Answer 1

My case is that I want to inject HTML after the li tag but only inside myList.

Other than for trivial cases where it's easy to write a "quick, hacky" script to get the job done, you should never use regular expressions to parse HTML.

A "quick, hacky" script in this case could be e.g. to search for:

<ul class="myList">.*<li>([^<]*)</li>(?=.*</ul>)

(Note: this probably needs to be a multi-line search; if there's no option for this then replace .* with [\s\S]*.)

...And then replace the value of the first match group (probably represented by $1 or \1, depending on how you do this).

However, as per my link above, I'd like to emphasise that this is not a perfect answer. It is literally impossible to perfectly parse HTML with a regular expression.

To do this "properly", you must use an XML parser instead.