jquery windows, documents, Web pages a variety of highly accurate understanding _jquery

$ (document). Height (): Height of the entire page
$ (window). Height (): Height of the browser visual window
$ (window). scrolltop (): Height of the top of the browser's visual window from the top of the page (vertical offset)

A word to understand is this: when the Web scroll bar is pulled to the lowest end, $ (document). Height () = = $ (window). Height () + $ (window). scrolltop ().

$ (document) when the page is not high enough for the browser window. Height () returns $ (window). Height ().

It is not recommended to use $ ("html"). Height (), $ ("body"). Heights ().

Reason:

$ ("body"). Height (): The body may have a border, and the height will be higher than $ (document). Height () small;
$ ("html"). Height (): The height of the different browsers to get the meaning of the difference will be, the plain is that the browser is not compatible.
$ (window). Height () value problem, not return the height of the browser window?