a === b -> identical(a, b)

samples/swarm/swarm_ui_lib/touch/FxUtil.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Common effects related helpers.
  */
 class FxUtil {
   /** On transition end event. */
   static const TRANSITION_END_EVENT = 'webkitTransitionEnd';
@@ skipping 26 matching lines @@
   /** Apply a -webkit-transform using translate3d to an HTML element. */
   static void setWebkitTransform(
       Element el, num x, num y, [num z = 0,
       num rotation = null, num scale = null,
       num originX = null, num originY = null]) {
     final style = el.style;
     // TODO(jacobr): create a helper class that simplifies building
     // transformation matricies that will be set as CSS styles. We should
     // consider using CSSMatrix although that may be overkill.
     String transform = '${TRANSLATE_3D}(${x}px,${y}px,${z}px)';
-    if (rotation !== null) {
+    if (rotation != null) {
       transform = transform.concat(' ${ROTATE}(${rotation}deg)');
     }
-    if (scale !== null) {
+    if (scale != null) {
       transform = transform.concat(' ${SCALE}(${scale})');
     }
     style.transform = transform;
-    if (originX !== null || originY !== null) {
-      assert(originX !== null && originY !== null);
+    if (originX != null || originY != null) {
+      assert(originX != null && originY != null);
       style.transformOrigin = '${originX}px ${originY}px';
     }
   }
 
   /**
    * Determine the position of an [element] relative to a [target] element.
    * Moving the [element] to be a child of [target] and setting the
    * [element]'s top and left values to the returned coordinate should result
    * in the [element]'s position remaining unchanged while its parent is
    * changed.
@@ skipping 28 matching lines @@
     style.left = '${x}px';
     style.top = '${y}px';
   }
 }
 
 class TransitionTimingFunction {
   static const EASE_IN = 'ease-in';
   static const EASE_OUT = 'ease-out';
   static const EASE_IN_OUT = 'ease-in-out';
 }