What is the difference between RegExp’s exec() function and String’s match() function?

Question

If I run this:

/([^\/]+)+/g.exec('/a/b/c/d'); 

I get this:

["a", "a"] 

But if I run this:

'/a/b/c/d'.match(/([^\/]+)+/g); 

Then I get the expected result of this:

["a", "b", "c", "d"] 

What's the difference?

Answer 1

exec with a global regular expression is meant to be used in a loop, as it will still retrieve all matched subexpressions. So:

var re = /[^\/]+/g; var match;  while (match = re.exec('/a/b/c/d')) {     // match is now the next match, in array form. }  // No more matches. 

String.match does this for you and discards the captured groups.

Answer 2

One picture is better, you know...

re_once = /([a-z])([A-Z])/  re_glob = /([a-z])([A-Z])/g    st = "aAbBcC"    console.log("match once="+ st.match(re_once)+ "  match glob="+ st.match(re_glob))  console.log("exec once="+ re_once.exec(st) + "   exec glob="+ re_glob.exec(st))  console.log("exec once="+ re_once.exec(st) + "   exec glob="+ re_glob.exec(st))  console.log("exec once="+ re_once.exec(st) + "   exec glob="+ re_glob.exec(st))

See the difference?

Note: To highlight, notice that captured groups(eg: a, A) are returned after the matched pattern (eg: aA), it's not just the matched pattern.