Question

I am using the following regular expression in Javascript:

comment_body_content = comment_body_content.replace(
  /(<span id="sc_start_commenttext-.*<\/span>)((.|\s)*)(<span id="sc_end_commenttext-.*<\/span>)/,
  "$1$4"
);

I want to find in my HTML code this tag <span id="sc_start_commenttext-330"></span> (the number is always different) and the tag <span id="sc_end_commenttext-330"></span>. Then the text and HTML code between those tags should be deleted and given back.

Example before replacing:

Some text and code
<span id="sc_start_commenttext-330"></span>Some text and code<span id="sc_end_commenttext-330"></span>
Some Text and code

Example after replacing:

Some text and code
<span id="sc_start_commenttext-330"></span><span id="sc_end_commenttext-330"></span>
Some text and code

Sometimes my regular expression works and it replaces the text correctly, sometimes not – is there a mistake? Thank you for help!

Alex

Answer 1

You should use a pattern that matches the start with its corresponding end, for example:

/(<span id="sc_start_commenttext-(\d+)"><\/span>)[^]*?(<span id="sc_end_commenttext-\2"><\/span>)/

Here \2 in the end tag refers to the matched string of (\d+) which matches the digits 330 in the start tag. [^] is a simple expression for any character.