Document represents the entire document (for a webpage, including the entire webpage structure );
Document.doc umentelement is the root node of the entire document node tree, which is an HTML tag on the webpage;
Document. body is the body node in the entire document Dom node tree. The webpage contains the Body Tag Element.
Scrolltop:
VaR scroll = document.doc umentelement. scrolltop | document. Body. scrolltop;
VaR scroll = document.doc umentelement. scrolltop? Document.doc umentelement. scrolltop: Document. Body. scrolltop;
When a document uses a DTD, the value of document. Body. scrolltop is 0.
Zookeeper uses document.doc umentelement. scrolltop to get the length of the scroll bar rolled over;
Use document. Body. scrolltop to get the value when no document is defined using DTD.
Clientheight:
IE, chrome, Firefox
Document. Body. clientwidth ==> body object width
Document. Body. clientheight ==> body object height
Document.doc umentelement. clientwidth ==> visible area width
Document.doc umentelement. clientheight => visible area height
Opera
Document. Body. clientwidth ==> visible area width
Document. Body. clientheight ==> visible area height
Document.doc umentelement. clientwidth ==> Page Object width (that is, the width of the body object plus the margin width)
Document.doc umentelement. clientheight ==> Page Object height (that is, the height of the body object plus the margin height)
Old talk ~ Documentelement & Body