diff --git a/diff.js b/diff.js
new file mode 100644
index 0000000..b6d3c68
--- /dev/null
+++ b/diff.js
@@ -0,0 +1,275 @@
+/**********************************************************************
+* 
+*
+*
+**********************************************************************/
+((typeof define)[0]=='u'?function(f){module.exports=f(require)}:define)
+(function(require){ var module={} // make module AMD/node compatible...
+/*********************************************************************/
+
+
+
+
+/*********************************************************************/
+// Diff base format:
+// 	{
+// 		varsion: '1.0',
+// 		options: {
+// 		},
+// 		
+// 		diff: <diff-format>,
+// 	}
+//
+// Diff format:
+//	[
+//	]
+//
+//
+//
+/*********************************************************************/
+
+var EMPTY = {type: 'EMPTY'}
+
+
+// Helpers...
+// XXX should we handle properties???
+var _diff_items = function(diff, A, B, options, filter){
+	// JSON mode -> ignore attr order...
+	var kA = Object.keys(A)
+	var kB = Object.keys(B)
+
+	if(filter){
+		kA = kA.filter(filter)
+		kB = kB.filter(filter)
+	}
+
+	var B_index = kB.reduce(function(res, k){
+		res[k] = null 
+		return res
+	}, {})
+
+	// items...
+	var items = kA
+			// A keys...
+			.map(function(ka){
+				var res = [ka, 
+					_diff(
+						A[ka], 
+						ka in B_index ? B[ka] : EMPTY, 
+						options)] 
+				// remove seen keys...
+				delete B_index[ka]
+				return res
+			})
+			// keys present only in B...
+			.concat(Object.keys(B_index)
+				.map(function(kb){
+					return [kb, 
+						_diff(
+							EMPTY, 
+							B[kb],
+							options)]}))
+			// cleanup...
+			.filter(function(e){
+				return e[1] !== null })
+	items.length > 0
+		&& (diff.items = (diff.items || []).concat(items))
+
+	return diff
+}
+var _diff_item_order = function(diff, A, B, options, filter){
+	var kA = Object.keys(A)
+	var kB = Object.keys(B)
+
+	if(filter){
+		kA = kA.filter(filter)
+		kB = kB.filter(filter)
+	}
+
+	var item_order = _diff(kA, kB, {mode: 'JSON'})
+	item_order != null 
+		&& (diff.item_order = item_order)
+
+	return diff
+}
+
+
+// Format:
+// 	- no difference...
+// 		null
+// 		
+// 	- A and/or B is a basic value...
+// 		{
+// 			type: 'Basic',
+// 			
+// 			A: <value>,
+// 			B: <value>,
+// 		}
+// 		
+// 	- A and B are arrays...
+// 		{
+// 			type: 'Array',
+// 			// holds both index and attribute keys (mode-dependant)...
+// 			
+// 			items: [
+// 				[<key>, <diff>],
+// 				...
+// 			],
+// 			// only for non-index keys...
+// 			item_order: <array-diff>,
+// 		}
+// 		
+// 	- A and B are objects...
+// 		{
+// 			type: 'Object',
+// 			
+// 			items: [
+// 				[<key>, <diff>],
+// 				...
+// 			],
+// 			item_order: <array-diff>,
+// 		}
+// 
+// 		
+// NOTE: this will include direct links to items.
+// XXX check seen -- avoid recursion...
+// XXX revise format...
+var _diff =
+function(A, B, options){
+	options = options || {}
+
+	// same object...
+	// XXX this will miss things like:
+	// 			new Number(123) vs. 123
+	//		...would need to also include .value (i.e. .valueOf()) and 
+	//		treat the thing as object...
+	if(A === B || A == B){
+	//if(A === B || (options.mode == 'JSON' && A == B)){
+		return null
+	}
+
+	// basic types...
+	if(typeof(A) != 'object' || typeof(B) != 'object'){
+		return {
+			type: 'Basic',
+			//values: [A, B],
+			A: A,
+			B: B,
+		}
+	}
+
+	// Array...
+	// XXX check seen -- avoid recursion...
+	if(A instanceof Array && B instanceof Array){
+		var res = {
+			type: 'Array',
+		}
+
+		// indexed items...
+		_diff_items(res, A, B, options, 
+			function(e){ return e == 0 || !!(e*1) })
+
+		// attributes... 
+		options.mode != 'JSON'
+			&& _diff_items(res, A, B, options, 
+				function(e){ return !(e == 0 || !!(e*1)) })
+			// attributes order...
+			&& _diff_item_order(res, A, B, options, 
+				function(e){ return !(e == 0 || !!(e*1)) })
+
+		return (res.items || []).length > 0 ? res : null
+
+	// Object...
+	// NOTE: this will handle ONLY own keys...
+	// XXX check seen -- avoid recursion...
+	// XXX handle prototyping... (???)
+	} else {
+		var res = {
+			type: 'Object',
+		}
+
+		_diff_items(res, A, B, options)
+
+		// XXX this should be applicable to JSON too...
+		options.mode != 'JSON'
+			&& _diff_item_order(res, A, B, options)
+
+		// .constructor...
+		if(options.mode != 'JSON'){
+			A.constructor !== B.constructor
+				&& (res.constructors = [A.constructor, B.constructor])
+
+			// XXX should we diff constructors???
+
+			// XXX .__proto___ (???)
+		}
+
+		return ((res.item_order || []).length + (res.items || []).length) == 0 ? null : res
+	}
+}
+
+
+// XXX need to track order very carefully here... (???)
+var flatten = 
+function(diff, res, path){
+	res = res || []
+	path = path || []
+
+	// no difference...
+	if(diff == null){
+		return res
+
+	// Basic...
+	} else if(diff.type == 'Basic'){
+		res.push({
+			path: path,
+			A: diff.A,
+			B: diff.B,
+		})
+
+	// Array...
+	} else if(diff.type == 'Array'){
+		diff.items.forEach(function(e){
+			var i = e[0]
+			var v = e[1]
+			var p = path.concat([i])
+
+			flatten(v, res, p)
+		})
+
+	// Object...
+	} else if(diff.type == 'Object'){
+		diff.items.forEach(function(e){
+			var i = e[0]
+			var v = e[1]
+			var p = path.concat([i])
+
+			flatten(v, res, p)
+		})
+
+	// Other...
+	// XXX revise this...
+	} else {
+		throw new TypeError('Unknown diff type: '+ diff.type)
+	}	
+
+	return res
+}
+
+
+var diff =
+module.diff = 
+function(A, B, options){
+}
+
+
+var patch =
+module.patch = 
+function(diff, obj){
+}
+
+
+
+
+/**********************************************************************
+* vim:set ts=4 sw=4 :                               */ return module })