plugin

this is a demo page to create jquery plugins !

reference:
https://stackoverflow.com/questions/1117086/how-to-create-a-jquery-plugin-with-methods?answertab=votes#tab-top

https://stackoverflow.com/questions/2534436/jquery-plugin-adding-callback-functionality
带参数
https://coderwall.com/p/gnkbzq/adding-a-callback-handler-to-a-jquery-plugin