Height of an element relative to the element's offsetParent.
Syntax and values
var intElemOffsetHeight = document.getElementById(id_attribute_value).offsetHeight;
intElemOffsetHeight is a variable storing an integer corresponding to the offsetHeight pixel value of the element. offsetHeight is a read-only property.
Description
Typically, an element's offsetHeight is a measurement which includes the element borders, the element vertical padding, the element horizontal scrollbar (if present, if rendered) and the element CSS height.
Non-scrollable elements (CSS overflow not set or set to visible) will have equal offsetHeight and scrollHeight (is this right? scrollHeight doesn't include the border, while offsetHeight would include border).
For the document body object, the measurement includes total linear content height instead of the element CSS height. Floated elements extending below other linear content are ignored.