Regular Expressions 101

Group 1(<img(?!.*?alt=(['"]).*?\2)[^>]*)

<imgthe literal text <img (case sensitive)

Negative Lookahead(?!.*?alt=(['"]).*?\2)

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

alt=the literal text alt= (case sensitive)

Group 2(['"])

Character Class['"]

'the literal ' (39₁₀ / 47₈ / 27₁₆)

"the literal " (34₁₀ / 42₈ / 22₁₆)

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

\2the text saved by group 2

Negated Character Class[^>]*

*matches any number of characters outside the set below:

>the literal > (62₁₀ / 76₈ / 3E₁₆)

Group 3(>)

>the literal > (62₁₀ / 76₈ / 3E₁₆)

Global pattern flags

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

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(<img(?!.*?alt=(['"]).*?\2)[^>]*)(>)

New

<html>
<body>
<img src="tos.jpg">

<img src="hfgfg.jpg" alt="texter alternatif">