Question

I’m reading something that mentions prefix regular expressions, and sites as an example /^joey/

What’s a prefix regular expression? Does that mean it starts with a caret?

Answer 1

It’s not a standard term. Whoever wrote that obviously means a regex that matches only at the beginning of the target text, as the other responders have said. The caret is usually used for that purpose, but it can also mean the beginning of a logical line, if the match is being performed in multiline mode. Many regex flavors support an additional construct that matches the very beginning of the text regardless of the matching mode, \A being its usual form.

For more details, read this.