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

tools/testing/legpad/legpad.dart

 // Copyright (c) 2012, 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.
 
 #import("dart:html", prefix:"html");
 #import('../../../lib/compiler/compiler.dart', prefix: "compiler_lib");
 #import('../../../lib/uri/uri.dart', prefix:"uri_lib");
 
 /**
  * This is the entrypoint for a version of the leg compiler that
@@ skipping 24 matching lines @@
 
   String readAll(String filename) {
     String text = getText(idOfFilename(filename));
     print("read $filename (${text.length} bytes)");
     return text;
   }
 
   void diagnosticHandler(uri_lib.Uri uri, int begin, int end,
                                  String message, bool fatal) {
     warnings.add(message);
-    if (uri !== null) {
+    if (uri != null) {
       warnings.add(" ($uri: $begin, $end)");
     }
     if (fatal) {
       warnings.add(" (fatal)");
     }
     warnings.add("\n");
   }
 
   Future<String> readUriFromString(uri_lib.Uri uri) {
     Completer<String> completer = new Completer<String>();
     completer.complete(readAll(uri.toString()));
     return completer.future;
   }
 
   /**
    * Returns the id of the <script> element that contains
    * the contents of this file.  (Replace all slashes
    * and dots in the file name with underscores.)
    */
   String idOfFilename(String filename) {
     return filename.replaceAll("/", "_").replaceAll(".", "_");
   }
 
   void run() {
     String mainFile = getText(MAIN_ID);
     setText("input", readAll(mainFile));
     Stopwatch stopwatch = new Stopwatch()..start();
     runLeg();
     int elapsedMillis = stopwatch.elapsedMilliseconds;
-    if (output === null) {
+    if (output == null) {
       output = "throw 'dart2js compilation error';\n";
     }
 
     setText("output", output);
     setText("warnings", warnings.toString());
     int lineCount = lineCount(output);
     String timing = "generated $lineCount lines "
         "(${output.length} characters) in "
         "${((elapsedMillis) / 1000).toStringAsPrecision(3)} seconds";
     setText("timing", timing);
@@ skipping 21 matching lines @@
          libraryRoot, readUriFromString, diagnosticHandler, compilerArgs);
 
     if (futureJavascript == null) {
       return;
     }
     output = futureJavascript.value;
   }
 
   void setText(String id, String text) {
     html.Element element = html.document.query("#$id");
-    if (element === null) {
+    if (element == null) {
       throw new Exception("Can't find element $id");
     }
     element.innerHTML = htmlEscape(text);
   }
 
   String getText(String id) {
     html.Element element = html.document.query("#$id");
-    if (element === null) {
+    if (element == null) {
       throw new Exception("Can't find element $id");
     }
     return element.text.trim();
   }
 
   // TODO(mattsh): should exist in standard lib somewhere
   static String htmlEscape(String text) {
     return text.replaceAll('&', '&amp;').replaceAll(
         '>', '&gt;').replaceAll('<', '&lt;');
   }
 }