Q:

How can I get the div information via js? 

For example, I have div named  $(".aDiv"), how can I get the $(".aDiv") position, and the information about $(".Div") using js?  thank you. 

A:

It depends what information you're after.   For the position for example, there's .position() (relative to the offset parent) and .offset() (relative to the document), like this:
var topCornerFromDocument = $(".aDiv").offset().top;
//or...
var leftCornerFromDocument = $(".aDiv").offset().left;

For other information there are many functions it depends what you're after - .attr() for attributes, .css() for style properties, etc.