1 files changed, 22 insertions, 0 deletions
diff --git a/js/jquery.onscreen.js b/js/jquery.onscreen.js
new file mode 100644
index 000000000..bbd1f3d4d
--- /dev/null
+++ b/js/jquery.onscreen.js
@@ -0,0 +1,22 @@
+// onScreen jQuery plugin v0.2.1
+// (c) 2011 Ben Pickles
+//
+// http://benpickles.github.com/onScreen
+//
+// Released under MIT license.
+;(function($) {
+  $.expr[":"].onScreen = function(elem) {
+    var $window = $(window)
+    var viewport_top = $window.scrollTop()
+    var viewport_height = $window.height()
+    var viewport_bottom = viewport_top + viewport_height
+    var $elem = $(elem)
+    var top = $elem.offset().top
+    var height = $elem.height()
+    var bottom = top + height
+
+    return (top >= viewport_top && top < viewport_bottom) ||
+           (bottom > viewport_top && bottom <= viewport_bottom) ||
+           (height > viewport_height && top <= viewport_top && bottom >= viewport_bottom)
+  }
+})(jQuery);