Regular Expressions 101

Explanation
Pro

Group 1(;\s*charset\s*=.[^\;]+)

;the literal ; (59₁₀ / 73₈ / 3B₁₆)

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

charsetthe literal text charset (case sensitive)

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

=the literal = (61₁₀ / 75₈ / 3D₁₆)

.any character (except for line terminators)

Negated Character Class[^\;]+

+matches at least one character outside the set below:

\;the literal ; (59₁₀ / 73₈ / 3B₁₆)

Detailed match information will be displayed here automatically.

25 tokens

(;\s*charset\s*=.[^\;]+)

New

application/vnd.obi.companion.customer+json;version=1;	charset=ISO-8859-1     ;       return null;