1 files changed, 30 insertions, 0 deletions
diff --git a/railties/html/javascripts/prototype.js b/railties/html/javascripts/prototype.js
index 5042e3304d..2541866ccb 100644
--- a/railties/html/javascripts/prototype.js
+++ b/railties/html/javascripts/prototype.js
@@ -452,3 +452,33 @@ Effect.Highlight.prototype = {
     element.style.backgroundColor = "#ffff" + current.toColorPart();
   }
 }
+
+
+Effect.Fade = Class.create();
+Effect.Fade.prototype = {
+  initialize: function(element) {
+    this.element = $(element);
+    this.start  = 100;
+    this.finish = 0;
+    this.current = this.start;
+    this.fade();
+  },
+  
+  fade: function() {
+    if (this.isFinished()) { this.element.style.display = 'none'; return; }
+    if (this.timer) clearTimeout(this.timer);
+    this.setOpacity(this.element, this.current);
+    this.current -= 10;
+    this.timer = setTimeout(this.fade.bind(this), 100);
+  },
+  
+  isFinished: function() {
+    return this.current <= this.finish;
+  },
+  
+  setOpacity: function(element, opacity) {
+    opacity = (opacity == 100) ? 99.999 : opacity;
+    element.style.filter = "alpha(opacity:"+opacity+")";
+    element.style.opacity = opacity/100;
+  }
+}
+\ No newline at end of file