Regular Expressions 101

Explanation
Pro

Atomic Group(?><.+?>)*

*repeats the group contents below any number of times:

<the literal < (60₁₀ / 74₈ / 3C₁₆)

.+?any character (except for line terminators), repeated at least once

>the literal > (62₁₀ / 76₈ / 3E₁₆)

Group 1((["'])(?:|(?:.*?)(?:[^\\]|[^\\]?(?:\\{2})+))\2)?

?repeats the group contents below at most once:

Group 2(["'])

Character Class["']

"the literal " (34₁₀ / 42₈ / 22₁₆)

'the literal ' (39₁₀ / 47₈ / 27₁₆)

Non-Capturing Group(?:|(?:.*?)(?:[^\\]|[^\\]?(?:\\{2})+))

1st Alternative — matches an empty string

2nd Alternative(?:.*?)(?:[^\\]|[^\\]?(?:\\{2})+)

Non-Capturing Group(?:.*?)

.*?any character (except for line terminators), repeated any number of times

Non-Capturing Group(?:[^\\]|[^\\]?(?:\\{2})+)

1st Alternative[^\\]

Negated Character Class[^\\]

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

2nd Alternative[^\\]?(?:\\{2})+

Negated Character Class[^\\]?

?matches at most one character outside the set below:

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

Non-Capturing Group(?:\\{2})+

+repeats the group contents below at least once:

\\{2}the literal \ (92₁₀ / 134₈ / 5C₁₆) , repeated exactly 2 times

\2the text saved by group 2

Global pattern flags

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

Detailed match information will be displayed here automatically.

25 tokens

(?><.+?>)*((["'])(?:|(?:.*?)(?:[^\\]|[^\\]?(?:\\{2})+))\2)?

New

<abc "sss"><span class="key" id="id1">'while'</span>"te\"s\\t2"<"fff">"test3"</A>

<abc "sss"><span class="key" id="id1">'while'</span>"te\"s\\t2"<"fff">"test3"</A>