singleton/singleton.html

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Singleton</title>
</head>
<body>
<script>
var obj = {
	myProp: 'myValue'
};

var obj2 = {
	myProp: 'myValue'
};

console.log('obj === obj2');
console.log(obj === obj2); //false
console.log('----------------------------------');
//-----------------------------------------------
//儲存在靜態屬性中的實體
function Universe(){
	if(typeof Universe.instance === 'object'){
		return Universe.instance;
	}

	this.start_time = 0;
	this.bang = 'Big';

	Universe.instance = this;
};

var uni = new Universe();
var uni2 = new Universe();
console.log('uni === uni2');
console.log(uni === uni2); //true

Universe.instance = null; //公開屬性，被修改了...
var uni3 = new Universe();
console.log(uni === uni3); //false
console.log('----------------------------------');
//-----------------------------------------------
//儲存在Closure中的實體
UniverseC.prototype.inNothing = true;

function UniverseC(){
	var instance = this;

	this.start_time = 0;
	this.bang = 'Big';

	//重新定義建構式
	UniverseC = function(){
		return instance;
	};
};

var uni4 = new UniverseC();
var uni5 = new UniverseC();
console.log('uni4 === uni5');
console.log(uni4 === uni5); //true
console.log('----------------------------------');

//測試是否遺失之後加上去的屬性
UniverseC.prototype.inEverything = true;
var uni6 = new UniverseC();

console.log(uni4.inNothing); //true
console.log(uni4.inEverything); //undefined
console.log(uni6.inNothing); //true
console.log(uni6.inEverything); //undefined

console.log('----------------------------------');
console.log(uni4.constructor.name); //UniverseC
console.log(uni4.constructor === UniverseC); //false

console.log(uni4.constructor); //最初定義的UniverseC
console.log(UniverseC); //重新定義的UniverseC
console.log('----------------------------------');
//-----------------------------------------------
//修改儲存在Closure中的實體
UniverseM.prototype.inNothing = true;
function UniverseM(){
	var instance;

	UniverseM = function UniverseM(){
		return instance;
	};

	UniverseM.prototype = this;
	instance = new UniverseM();
	instance.constructor = UniverseM();

	instance.start_time = 0;
	instance.bang = 'Big';

	return instance;
};

var uni7 = new UniverseM();
var uni8 = new UniverseM();

console.log(uni7 === uni8); //true

UniverseM.prototype.inEverything = true;
console.log(uni7.constructor === UniverseM); //true

console.log(uni7.constructor); //最初定義的UniverseM
console.log(UniverseM); //重新定義的UniverseM
console.log('----------------------------------');
//-----------------------------------------------
var UniverseN;
(function(){
	var instance;
	UniverseN = function UniverseN(){
		if(instance){
			return instance;
		}
		instance = this;

		this.start_time = 0;
		this.bang = 'Big';
	};
}());

var uni9 = new UniverseN();
var uni10 = new UniverseN();

console.log(uni9 === uni10); //true

UniverseN.prototype.inEverything = true;
console.log(uni9.constructor === UniverseN); //true

console.log(uni9.constructor); //最初定義的UniverseN
console.log(UniverseN); //重新定義的UniverseN
console.log('----------------------------------');
</script>
</body>
</html>