Mimics a custom 'appear' event, which fires when an element scrolls into view or otherwise becomes visible to the user.

$('#foo').appear(function() {
  $(this).text('Hello world');
});

This plugin can be used to prevent unnecessary requests for content that's hidden or outside the viewable area.

$('#foo').appear(function() {
  $(this).text('Hello world');
},{accX: 50, accY: 100});

Will fire 'appear' event with accuracy 50px in X and 100px in Y

http://bas2k.ru/