diff -r b157a354003f -r a2871a3fd4c5 emul/src/main/resources/org/apidesign/vm4brwsr/emul/java_lang_String.js
--- a/emul/src/main/resources/org/apidesign/vm4brwsr/emul/java_lang_String.js	Tue Jan 15 12:38:49 2013 +0100
+++ b/emul/src/main/resources/org/apidesign/vm4brwsr/emul/java_lang_String.js	Tue Jan 15 12:44:33 2013 +0100
@@ -7,12 +7,15 @@
   this.jvmName = sig;
   return this;
 };
-Array.prototype.at = function(indx) {
+Array.prototype.at = function(indx, value) {
   if (indx < 0 || indx > this.length) {
       var e = vm.java_lang_ArrayIndexOutOfBoundsException(true);
       e.constructor.cons__VLjava_lang_String_2.call(e, indx.toString());
       throw e;
   }
+  if (arguments.length === 2) {
+      this[indx] = value;
+  }
   return this[indx];
 };
 Array.prototype.getClass__Ljava_lang_Class_2 = function() {