Anytime I have to play with regular expressions, I use one of the online regex testing web sites to come up with the regex I need. Last couple of times I had to come up with a regex for most common everyday stuff like dates and such. Oh yeah, last time it was date actually. I had a server response that had a date in the format yyyy-mm-dd , ISO format. I was working with JavaScript, and initially I was naive to use the Date class to parse the date in the response. Turned that there is difference in the way the date is interpreted by Firefox and other browsers. Ok, this is not a rant post about the Date class but actually share some sites that help you with regular expressions, of course at different levels. Here is a list of such sites: http://regexpal.com/ http://regex101.com http://rubular.com/ https://www.debuggex.com/ http://www.freeformatter.com/regex-tester.html In the above list, I like the last but not the least - freeformatter.com . The cool thing about freeformatter ...
Another effective [debugging] technique is to explain your code to someone else. This will often cause you to explain the bug to yourself. Sometimes it takes no more than a few sentences, followed by an embarrassed "Never mind. I see what's wrong. Sorry to bother you." This works remarkbly well; you can even use non-programmers as listeners. - From "The Practice of Programming" by Brian W Kernighan & Rob Pike.