Regular Expressions 101

Explanation

Pro

1st Alternative(<(?!a\b)(\w+)\b(?>(?:(?!</?\2\b).)+(?1)?)*</\2>)(*SKIP)(*F)

Group 1(<(?!a\b)(\w+)\b(?>(?:(?!</?\2\b).)+(?1)?)*</\2>)

<the literal < (60₁₀ / 74₈ / 3C₁₆)

Negative Lookahead(?!a\b)

athe literal a (97₁₀ / 141₈ / 61₁₆) (case insensitive)

\ban ASCII word boundary

Group 2(\w+)

\w+any word character, repeated at least once

\ban ASCII word boundary

Atomic Group(?>(?:(?!</?\2\b).)+(?1)?)*

*repeats the group contents below any number of times:

Non-Capturing Group(?:(?!</?\2\b).)+

+repeats the group contents below at least once:

Negative Lookahead(?!</?\2\b)

<the literal < (60₁₀ / 74₈ / 3C₁₆)

/?optionally matches the literal / (47₁₀ / 57₈ / 2F₁₆)

\2the text saved by group 2

\ban ASCII word boundary

.any character

(?1)?optionally calls group 1 as a subroutine

</the literal text </

\2the text saved by group 2

>the literal > (62₁₀ / 76₈ / 3E₁₆)

(*SKIP)acts like (*PRUNE), but the next unanchored match attempt starts where (*SKIP) was reached instead of at the next subject character

(*F)forces the current match attempt to fail at this position

2nd Alternative<a\b.*?</a>\s*

<athe literal text <a (case insensitive)

\ban ASCII word boundary

.*?any character, repeated any number of times

</a>the literal text </a> (case insensitive)

\s*any whitespace character, repeated any number of times

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

s modifier: single line. Allows a dot to match line terminators

Match Information

Detailed match information will be displayed here automatically.

Quick Reference

25 tokens

Regular Expression

(<(?!a\b)(\w+)\b(?>(?:(?!</?\2\b).)+(?1)?)*</\2>)(*SKIP)(*F)|<a\b.*?</a>\s*

New

Hi Hello <a href="#">World</a>. This is
<div class="some">testing <a href="#">content</a>. some more content</div>
<a href="#">World</a>
<div class="some">
  <div class="some">testing <a href="#">content</a>. some more content</div>
  <span>abc</span>
  <a href="#">World</a>
</div>
<a href="#">World</a>

Extraction

Hi Hello <a href="#">World</a>. This is
<div class="some">testing <a href="#">content</a>. some more content</div>
<a href="#">World</a>
<div class="some">
  <div class="some">testing <a href="#">content</a>. some more content</div>
  <span>abc</span>
  <a href="#">World</a>
</div>
<a href="#">World</a>