Underscore functions transparently unwrap knockout observables

knockoutifyUnderscore.js

 //make a limited set of underscore functions transparently unwrap knockout observables
  (function knockoutifyUnderscore(_) {
    var unwrap = ko.utils.unwrapObservable;
   
		//These can be shimed in a standard way
		var koFriendly = ['map', 'filter', 'find', 'each', 'findBy', 'first', 'last', 'head', 'tail', 'union', 'compact', 'flatten', 'difference', 'without'];
		var oldMap = _.map;
		for (var _i = 0; _i < koFriendly.length; _i++) {
			(function(fnName) {
				var originalFn = _[fnName];
				_[fnName] = function() {
					var args;
					args = oldMap(arguments, unwrap);
					return originalFn.apply(_, args);
				};
			})(koFriendly[_i]);
		}
 
		//These underscore commands need special attention
		_.mixin({
			where: function(collection, query) {
				query = _.mapObject(query, function(val, key){
					return [key, unwrap(val)]
				});
				return _.filter(collection, function(item){
					return _.all(query, function(queryVal, key) {
						return queryVal === unwrap(item[key]);						
					})
				});
			}
		});
	})(_)