cas_start.js

// requires Store.js
OrgSync.cache = (function(store) {
	if (!store || typeof store.get !== 'function' || typeof store.set !== 'function') {
		throw new Error("Store API not defined.");
	}
	
	var api = {};
	
	var now = function () {
		return parseInt((new Date).getTime() / 1000);
	};
	
	var is_expired = function (data) {
		if (!data || !data.expires || data.expires >= now()) {
			console.log("data expired!");
		} else {
			console.log("data NOT expired!");
		}
		return !data || !data.expires || data.expires >= now();
	}
	
	api.cas = function () {
		if (arguments.length < 2) {
			throw new Error("Usage: cas(key, [expires_in,], callback, [callback_arg])");
		}
		
		var args         = Array.prototype.slice.call(arguments),
				key          = args.shift(),
				expires_in   = typeof args[0] === 'number' ? args.shift() : null,
				on_miss      = args.shift(),
				on_miss_args = args;
		
		return on_miss.apply(null, on_miss_args);
	};
	
	return api;
})(store);

// OrgSync.cache.cas("test key", function() { return arguments.length; }, 1,2,3) === 3