try see compare understand learn JavaScript Regular Expressions
Practice with a string and pattern
Enter input string
Enter regex pattern
?
/(Re|Ja|Ex).+?\b/gCount:4
jsRegex Workouts
try, see, compare, understand and learn JavaScript Regular Expressions
matchposition$1
Regex2Re
JavaScript57Ja
Regular68Re
Expressions76Ex

Addpanel against a single text or regexp respectively.