diff --git a/patcher.js b/patcher.js
index f004c99..ab3e633 100644
--- a/patcher.js
+++ b/patcher.js
@@ -9,7 +9,7 @@
 //-------------------------------------------------------------
 
 //node.js interoperability
-if(typeof(exports) == "undefined") {
+if(typeof(exports) === "undefined") {
   var patcher = {};
 }
 
@@ -63,6 +63,9 @@ function computePatch(prev, next, update_in_place) {
   
     //Add _ to escape ids which start with _
     var target_id = (typeof(id) == "string" && id.charAt(0) == "_" ? "_" + id : id);
+    if( typeof(target_id) === 'number' ){
+    	target_id = '_'+target_id;
+    };
     
     //First, check if the element exists and types match
     if(id in prev && typeof(prev[id]) == typeof(next[id])) {
@@ -162,14 +165,34 @@ function applyPatch(obj, patch) {
   
   for(i in patch) {
     //Unescape underscore
-    var t = (typeof(i) == "string" && i.charAt(0) == "_" ? i.substring(1) : i);
+    //var t = (typeof(i) == "string" && i.charAt(0) == "_" ? i.substring(1) : i);
+	if( typeof(i) === 'string' 
+     && i.length > 1 
+     && i.charAt(0) == '_' 
+     && i.charAt(1) == '_'  ) {
+      // string staring with _ which is escaped
+      var t = i.substring(1);
+      
+    } else if( typeof(i) === 'string' 
+        && i.length > 0
+        && i.charAt(0) == '_'  ) {
+      // escaped index
+      t = 1 * i.substring(1);
+      
+    } else {
+      t = i;
+    };
     
     if(typeof(obj[t]) == typeof(patch[i]) &&
       typeof(patch[i]) == "object" &&
-      patch[i] != null &&
-      (obj[t] instanceof Array) == (patch[i] instanceof Array)) {
-      applyPatch(obj[t], patch[i]);
-      continue;
+      patch[i] != null ) {
+      if( (obj[t] instanceof Array) == (patch[i] instanceof Array) ) {
+        applyPatch(obj[t], patch[i]);
+        continue;
+      } else if( (obj[t] instanceof Array) && false == (patch[i] instanceof Array) ) {
+        applyPatch(obj[t], patch[i]);
+        continue;
+      };
     }
     obj[t] = patch[i]
   }
@@ -177,7 +200,7 @@ function applyPatch(obj, patch) {
 
 
 //Add methods to patcher
-if(typeof(exports) == "unedefined") {
+if(typeof(exports) === "undefined") {
   patcher.computePatch = computePatch;
   patcher.applyPatch   = applyPatch;
 } else {
diff --git a/testcases.js b/testcases.js
new file mode 100644
index 0000000..62fcd0d
--- /dev/null
+++ b/testcases.js
@@ -0,0 +1,150 @@
+// Test cases to be run using rhino
+// > rhino -f testcases.js
+
+load('./patcher.js');
+
+var enableDebugLog = false;
+var testCount = 0;
+var testFailed = 0;
+
+function debug() {
+	if( enableDebugLog ) {
+		if( typeof(console) !== 'undefined' 
+		 && null !== console 
+		 && typeof(console.log) === 'function'
+		) {
+			try { console.log.apply(console,arguments); }
+				catch(e) {};
+		} else if( typeof(print) === 'function' ){
+			print.apply(null, arguments);
+		};
+	};
+};
+
+function printLog(str){
+	print(str);
+};
+
+/*
+ * Test object equality using facilities in
+ * patcher
+ * @param o1 {Object} One of the objects to compare
+ * @param o2 {Object} The other object to compare
+ * @return {Boolean} True if the objects are equivalent. Otherwise, false.
+ */
+function areObjEqual(o1,o2){
+	if( o1 === o2 ) {
+		return true;
+	} else if( typeof(o1) === 'undefined' && typeof(o2) === 'undefined' ){
+		return true;
+	} else if( typeof(o1) === 'undefined' ){
+		return false;
+	} else if( typeof(o2) === 'undefined' ){
+		return false;
+	} else if( null === o1 ){
+		return false;
+	} else if( null === o2 ){
+		return false;
+	} else {
+		var patch = patcher.computePatch(o1, o2);
+		return (patch === null);
+	};
+};
+
+/*
+ * Performs a specific test
+ * @param testName {String} Name of test
+ * @param prev {Object} Original object
+ * @param next {Object} Updated object
+ * @param expected {Object} Expected patch to be generated between prev and next
+ */
+function patchTest(testName, prev, next, expected){
+	var patch = patcher.computePatch(prev, next);
+	debug(testName, patch);
+	var error = null;
+	if( ! areObjEqual(patch,expected) ) {
+		error = 'unexpected patch';
+		debug(testName+' patches(expected, actual)',expected,patch);
+	};
+	if( null != patch ) {
+		patcher.applyPatch(prev,patch);
+		if( ! areObjEqual(prev,next) ) {
+			error = 'patched object is not equivalent to expected result';
+			debug(testName+' patched object (expected,actual)',next,prev);
+		};
+	};
+	++testCount;
+	if( error ) {
+		++testFailed;
+		printLog(testName+' failed: '+error);
+	} else {
+		printLog(testName+' passed');
+	};
+};
+
+function main(){
+	testCount = 0;
+	testFailed = 0;
+
+	patchTest('identity.0',{},{},null);
+
+	patchTest('identity.1',{a:'1',b:'2'},{a:'1',b:'2'},null);
+	
+	patchTest('add.0',{},{a:1},{a:1});
+
+	patchTest('add.1',{a:'1'},{a:'1',b:{c:{d:'3'},e:4}},{b:{c:{d:'3'},e:4}});
+	
+	patchTest('remove.0',{a:1,b:2,c:3},{b:2,c:3},{_r:'a'});
+	
+	patchTest('remove.1',{a:1,b:2,c:3},{c:3},{_r:['a','b']});
+	
+	patchTest('remove.2',{a:1,b:2,c:3},{},{_r:['a','b','c']});
+
+	patchTest('object.0',{a:{b:'1',c:'3'}},{a:{b:'2',c:'3'}},{a:{b:'2'}});
+
+	patchTest('object.1',{a:{b:'1',c:'3'}},{a:{c:'3'}},{a:{_r:'b'}});
+
+	patchTest('object.2',{a:{b:'1',c:'3'}},{a:{}},{a:{_r:['b','c']}});
+
+	patchTest('object.3',{a:{b:'1',c:'3'}},{a:{d:'4'}},{a:{_r:['b','c'],d:'4'}});
+
+	patchTest('replace.0',{a:1},{a:'1'},{a:'1'});
+
+	patchTest('replace.1',{a:1},{a:{b:'1'}},{a:{b:'1'}});
+
+	patchTest('replace.2',{a:1},{a:[]},{a:[]});
+
+	patchTest('replace.3',{a:[]},{a:1},{a:1});
+
+	patchTest('replace.4',{a:1},{a:['a','b']},{a:['a','b']});
+	
+	patchTest('array.0',{a:[0,1]},{a:[0,1,2]},{a:{_2:2,_r:3}});
+	
+	patchTest('array.1',{a:[0,1,2]},{a:[0,1]},{a:{_r:2}});
+	
+	patchTest('array.2',{a:[0,1,2]},{a:[0,2]},{a:{_r:2,_1:2}});
+
+	patchTest('array.3',{a:[0,'1',{b:2,c:3}]},{a:[0,'1',{b:2,c:3}]},null);
+
+	patchTest('array.4',{a:[0,'1',{b:2,c:3}]},{a:['a','1',{b:2,c:3}]},{a:{_0:'a'}});
+
+	patchTest('array.5',{a:[0,'1',{b:2,c:3}]},{a:[0,{d:4},{b:2,c:3}]},{a:{_1:{d:4}}});
+
+	patchTest('array.6',{a:[0,'1',{b:2,c:3}]},{a:[0,'1','4']},{a:{_2:'4'}});
+
+	patchTest('array.7',{a:[0,'1',{b:2,c:3}]},{a:[0,'1',{b:4,c:3}]},{a:{_2:{b:4}}});
+
+	patchTest('array.8',{a:[0,'1',{b:2,c:3}]},{a:[{b:2,c:3}, 0,'1']},{a:{_0:{b:2,c:3}, _1:0, _2:'1'}});
+
+	patchTest('escape.0',{_a:1},{_a:2},{__a:2});
+
+	patchTest('escape.1',{__a:1},{__a:2},{___a:2});
+
+	patchTest('escape.2',{_a:1},{},{_r:'_a'});
+
+	patchTest('escape.3',{_a:1,_b:2},{},{_r:['_a','_b']});
+	
+	printLog('Completed: '+testCount+' Failures: '+testFailed)
+};
+
+main();
\ No newline at end of file