Factory
function ObjectFactory(ctor) {
var obj = {};
return function() {
if(typeof ctor.prototype === 'number')
obj.__proto__ = Object.prototype;
else
obj.__proto__ = ctor.prototype;
var ret = ctor.apply(obj, arguments);
return typeof ret == 'object' ? ret : obj;
}
}
function Point(x, y) { this.x = x; this.y = y }
// The following is equivalent to: var p1 = new Point(0, 0);
var p1 = ObjectFactory(Point)(0, 0);
Singleton
var createSingletonOf = function(ctor) {
var singleton;
return function() {
return singleton || (singleton = ObjectFactory(ctor).apply(null, arguments))
}
}
var point = createSingletonOf(Point);
var p2 = point(1,2);
var p3 = point(3,4); // p3 === p2
Observer
var Observer = (function() {
var listeners = [];
return {
listen: function(callback) { listeners.push(callback) },
trigger: function(res) { listeners.forEach(function(fn) { fn(res) }) },
observe: function(act) { this.trigger(act()) },
};
})();
Adaptor
// ThermometerFahr is an adapter of ThermometerCels
var ThermometerFahr = function() {
var thermoC = new ThermometerCels();
this.setTemperature(tempF) { thermoC.setTemperature((tempF?32)/1.8) }
this.getTemperature(tempF) { return thermoC.getTemperature()*1.8+32 }
}
var thermoF = new ThermometerFahr();
Decorator
Function.prototype.bind = function (scope) { // a helper function
var fn = this;
return function () {
return fn.apply(scope);
};
}
/* MethodProfiler class */
var MethodProfiler = function(obj) {
this.obj = obj;
this.timers = {};
for(var key in obj) {
if(typeof obj[key] !== 'function') continue;
(function(method) {
this[method] = function() {
this.tick(method);
var ret = obj[method].apply(obj, arguments);
this.log(method, this.getElapsedTime(method));
return ret;
}.bind(this);
}.bind(this))(key);
}
};
MethodProfiler.prototype = {
tick: function(method) {
this.timers[method] = (new Date()).getTime();
},
getElapsedTime: function(method) {
return (new Date()).getTime() - this.timers[method];
},
log: function(method, time) {
console.log('Elapsed time of executing ' + method + ' is ' + time + ' ms');
}
};
// Demonstration of usage
var test_target = { foo:function() { alert('hi there') } };
var profiler = new MethodProfiler(test_target);
// profiler is a decorator of test_target
profiler.foo();
