Add more type validation to codec.js

mojo/public/js/codec.js

Index: mojo/public/js/codec.js
diff --git a/mojo/public/js/codec.js b/mojo/public/js/codec.js
index 5440abed92d3651e684a492f97673bee286d9d68..f6b77ef05b27bc6cf0d773d52e5f5ae8e1f875b8 100644
--- a/mojo/public/js/codec.js
+++ b/mojo/public/js/codec.js
@@ -8,7 +8,9 @@ define("mojo/public/js/codec", [
 ], function(unicode, buffer) {
 
   var kErrorUnsigned = "Passing negative value to unsigned";
-  var kErrorArray = "Passing non-array-like to array";
+  var kErrorArray = "Passing non Array for array type";
+  var kErrorString = "Passing non String for string type";
+  var kErrorMap = "Passing non Map for map type";
 
   // Memory -------------------------------------------------------------------
 
@@ -353,7 +355,7 @@ define("mojo/public/js/codec", [
       this.encodePointer(val);
       return;
     }
-    if (val.length === undefined) {
+    if (!(val instanceof Array)) {
       throw new Error(kErrorArray);
     }
     var numberOfElements = val.length;
@@ -369,6 +371,10 @@ define("mojo/public/js/codec", [
       this.encodePointer(val);
       return;
     }
+    // This only accepts literal strings, not new String("foo").
+    if (typeof(val) !== "string") {

[hansmuller, 2014/12/16 01:10:41]

Don't you mean primitive strings? 

[eseidel, 2014/12/16 01:13:04]

I'm not sure what you mean.

I mean string literals, like "foo" vs. new String("foo").

I should probably should have written "string literals" isntead of "literal
strings" if that's what you mean?

+      throw new Error(kErrorString);
+    }
     var encodedSize = kArrayHeaderSize + unicode.utf8Length(val);
     var encoder = this.createAndEncodeEncoder(encodedSize);
     encoder.encodeString(val);
@@ -394,6 +400,9 @@ define("mojo/public/js/codec", [
       this.encodePointer(val);
       return;
     }
+    if (!(val instanceof Map)) {
+      throw new Error(kErrorMap);
+    }
     var encodedSize = kStructHeaderSize + kMapStructPayloadSize;
     var encoder = this.createAndEncodeEncoder(encodedSize);
     encoder.encodeMap(keyClass, valueClass, val);