來源:http://atedev.wordpress.com/2007/11/23/%E6%AD%A3%E8%A6%8F%E8%A1%A8%E7%A4%BA%E5%BC%8F-regular-expression/
and
http://neural.cs.nthu.edu.tw/jang/books/webprog/03jscript/reg3.asp?SessionCount=15