difference of top and left between Javascript and Jquery

1, top and left relative to the document

jquery 
.offset()

Get the current coordinates of the first element, or set the coordinates of every element, in the set of matched elements, relative to the document.

var top = $('#elementID').offset().top;var left = $('#elementID').offset().left;

native javascript
getBoundingClientRect, top-left relative to the top-left of the viewport.

var viewportOffset = el.getBoundingClientRect();// these are relative to the viewportvar top = viewportOffset.top;var left = viewportOffset.left;

2, top and left relative to the parent

jquery
.position()
Get the current coordinates of the first element in the set of matched elements, relative to the offset parent.

var topToParent = $('#elementID').position().top;var leftToParent = $('#elementID').position().left;

native javascript

.offsetTop, .offsetLeft

The HTMLElement.offsetTop read-only property returns the distance of the current element relative to the top of the offsetParent node.

var topToParent = element.offsetTop;var leftToParent = element.offsetLeft;

3,  Border 

native javascript
element.clientTop;

The width of the top border of an element in pixels. It does not include the top margin or padding. clientTop is read-only.
see:  https://developer.mozilla.org/en-US/docs/Web/API/Element/clientTop