jquery

1.  serialize function
1. https://api.jquery.com/serialize/
2. what if there are multiple ready function?
1. https://stackoverflow.com/questions/5263385/jquery-multiple-document-ready
3. debugging
1. all function must return
2. unique id of elements
3. event execution order
4. https://stackoverflow.com/questions/10638059/javascript-debugging-line-by-line-using-google-chrome
5.