JavaScript regex and exec()

Every time I use JavaScript's regular expressions I inevitably have to relearn something.  Today I am putting the finishing touches on a new web-based static analysis tool I'll blog about later, and I needed to do something simple: given a dehydra JS object that has been pushed through SpiderMonkey's uneval() function, I want to find and replace all instances of "Line: #," with the actual line of code I'm analyzing.  Using the js shell, I did some quick tests:

js> x
"blah blah blah line: 2, blah blah blah line: 3, blah blah line: 4, blah blah"
js> /line: (\d+),/g.exec(x);
["line: 2,", "2"]

No matter what I tried, this always gave me the first match, and no more.  Luckily, Gavin had the answer: exec() is meant to be called in a loop, and position info is cached.  It's about the least obvious API choice I can imagine for doing this, but here you are:

js> var r=/line: (\d+),/g; while (m=r.exec("blah blah blah line: 2, blah blah blah line: 3, blah blah line: 4, blah blah")) print(m);
line: 2,,2
line: 3,,3
line: 4,,4

Now you know, and I'll have something to search for on Google next time I have to relearn this!