within :: Position

within(element, x, y) -> Boolean Indicates whether the point x, y (measured from the top-left corner of the document) is within the boundaries of element. Must be called immediately before Position.overlap.

This function uses Position.cumulativeOffset to determine element’s offset from the top of the page, then combines those values with element’s height and width to identify the offsets of all four corners of the element. It then compares these coordinates to the x and y arguments, returning true if those coordinates fall within the bounding box of element.

Example

var element = $('some_positioned_element');

Position.cumulativeOffset(element);

// -> [100, 100] (item is 100px from the left and top edges of the page)

Element.getDimensions(element);

// -> { width: 150, height: 150 }

Position.within(element, 200, 200);

// -> true

Position.within(element, 260, 260);

// -> false

Prototype API 1.5.0 - prototypejs.org