Regular Expressions 101

Pro

^start of line

Positive Lookahead(?=.*param1=([^&]+)|)

1st Alternative.*param1=([^&]+)

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

param1=the literal text param1= (case sensitive)

Group 1([^&]+)

Negated Character Class[^&]+

+matches at least one character outside the set below:

&the literal & (38₁₀ / 46₈ / 26₁₆)

2nd Alternative — matches an empty string

Positive Lookahead(?=.*param2=([^&]+)|)

1st Alternative.*param2=([^&]+)

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

param2=the literal text param2= (case sensitive)

Group 2([^&]+)

Negated Character Class[^&]+

+matches at least one character outside the set below:

&the literal & (38₁₀ / 46₈ / 26₁₆)

2nd Alternative — matches an empty string

Positive Lookahead(?=.*param3=([^&]+)|)

1st Alternative.*param3=([^&]+)

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

param3=the literal text param3= (case sensitive)

Group 3([^&]+)

Negated Character Class[^&]+

+matches at least one character outside the set below:

&the literal & (38₁₀ / 46₈ / 26₁₆)

2nd Alternative — matches an empty string

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

$end of line

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.

25 tokens

^(?=.*param1=([^&]+)|)(?=.*param2=([^&]+)|)(?=.*param3=([^&]+)|).+$

New

?param1=test1&param2=test2&param3=test3
?param1=test1
?param2=test2&param1=test1