单例模式的基本结构：
MyNamespace.Singleton = function() {
return {};
}();
比如：
MyNamespace.Singleton = (function() {
return { // Public members.
publicAttribute1: true,
publicAttribute2: 10,
publicMethod1: function() {
...
},
publicMethod2: function(args) {
...
}
};
})();
但是，上面的Singleton在代码一加载的时候就已经建立了，怎么延迟加载呢？想象C#里怎么实现单例的:)采用下面这种模式：
MyNamespace.Singleton = (function() {
function constructor() { // All of the normal singleton code goes here.
...
}
return {
getInstance: function() {
// Control code goes here.
}
}
})();
具体来说，把创建单例的代码放到constructor里，在首次调用的时候再实例化：
完整的代码如下：
MyNamespace.Singleton = (function() {
var uniqueInstance; // Private attribute that holds the single instance.
function constructor() { // All of the normal singleton code goes here.
...
}
return {
getInstance: function() {
if(!uniqueInstance) { // Instantiate only if the instance doesn't exist.
uniqueInstance = constructor();
}
return uniqueInstance;
}
}
})();