Extracts the payload after a known prefix. extractPrefixPayload('scan:cal', 'scan:') -> 'cal'.
extractPrefixPayload('scan:cal', 'scan:')
The full command string.
The literal prefix to strip.
The trimmed payload, or '' when prefix not present or payload empty.
Extracts the payload after a known prefix.
extractPrefixPayload('scan:cal', 'scan:')-> 'cal'.