Simple jQuery plugin to determine if an element is within the viewport. Optional parameters allow the user to specify a minimum percentage of the element's dimensions that must be visible to qualify.
@param x - float values to test against, as a decimal value of how much of the element's width must be visible for the method to return true. defaults to 1 (100%)
@param y - float values to test against, as a decimal value of how much of the element's height must be visible for the method to return true. defaults to 1 (100%)
For example, passing $(element).isOnScreen(0.5, 0.5) would return true if the element had at least 50% of it’s height and width within the viewport rectangle. $(element).isOnScreen(0.1, 0.5) would return true if at least 10% of the width were visible and 50% of the height were visible. Omitting an argument (or passing null) defaults to 1 (or 100%).
Usage is simple
$('selector').isOnScreen(); // returns true if element is entirely within the viewport
$('selector').isOnScreen(0.5, 0.5); // returns true if element is at least 50% within the viewport