Helpful js functions for knockout.js library

ko.extras.js

//given an object and a white list; reset all knockout observables to undefined
	var reset = function (obj, whitelist) {
		for (var prop in obj) {
			if ( obj.hasOwnProperty(prop) && ko.isObservable(obj[prop]) && !ko.isComputed(obj[prop]) && whitelist.indexOf(prop) === -1 ) {
				obj[prop](undefined);
			}
		}
	};

//useful for when an object is used for the value property of a dropdown. Usage: "optionsAfterRender: setOptionValue('propertyName')"
var setOptionValue = function(propId){
		return function(option, item) {
			if(item === undefined) {
				option.value = '';
			}
			else {
				if(typeof(item[propId]) === typeof(function() {})) {
					option.value = item[propId]();
				}
				else{
					option.value = item[propId];
				}
			}
		};
	};