Fix regression in behavior of someElements.each(Element.toggle). [close prototypejs#136]

Author: savetheclocktower

src/prototype/dom/dom.js

@@ -274,6 +274,8 @@
 
   /**
    *  Element.toggle(@element[, bool]) -> Element
+   *  - bool (Boolean): Whether the element should be shown or hidden. If not
+        a boolean, this argument will be ignored.
    *
    *  Toggles the CSS `display` of `element`. Returns `element`.
    *  
@@ -284,6 +286,13 @@
    *  current state, but will use the `bool` argument instead if it's
    *  provided (`true` to show the element, `false` to hide it).
    *  
+   *  If the `bool` argument is not a boolean, **it will be ignored**. This
+   *  preserves the ability to toggle elements through comparisons (e.g.,
+   *  `errorElement.toggle(errors > 0)`) while also letting a user do
+   *  `someElements.each(Element.toggle)` without falling victim to 
+   *  JavaScript's famous [problems with variadic arguments](http://www.wirfs-brock.com/allen/posts/166).
+   *  
+   *  
    *  ##### Examples
    *  
    *      <div id="welcome-message">Welcome</div>
@@ -335,7 +344,7 @@
   **/
   function toggle(element, bool) {
     element = $(element);
-    if (Object.isUndefined(bool))
+    if (typeof bool !== 'boolean')
       bool = !Element.visible(element);
     Element[bool ? 'show' : 'hide'](element);
 

test/unit/dom_test.js

@@ -305,6 +305,10 @@ new Test.Unit.Runner({
     this.assert($('test-toggle-hidden').visible(), 'test-toggle-hidden 1');
     $('test-toggle-hidden').toggle();
     this.assert(!$('test-toggle-hidden').visible(), 'test-toggle-hidden 2');
+    
+    $('test-toggle-hidden', 'test-toggle-visible').each(Element.toggle);
+    this.assert(!$('test-toggle-visible').visible(), 'test-toggle-visible-3');
+    this.assert($('test-toggle-hidden').visible(), 'test-toggle-hidden-3');
   },
 
   testElementShow: function(){