通过示例解释构造对象中不同事物的行为：
// Defined as a variable from an anonymous function
// so that there is scope closure over variables
// shared across all instances and the prototype.
// If this isn't important, you don't need to close
// scope around it, so define directly
var ConstructedObject = (function constructorCreator () {
// Define any variables/methods to be shared across
// all instances but not polluting the namespace
var sharedVariable = 'foo';
// Next the actual constructor
function ConstructedObject () {
// Variables here are normally used to help
// each instance and will be kept in memory as
// long as the instance exists
var instanceVariable = 'bar';
// instance-specific properties get defined
// using the "this" keyword, these are the
// properties expected to be changed across
// each different instance
this.instanceProperty = true;
this.instanceMethod = function () { return instanceVariable; };
this.changeInstanceVar = function () { instanceVariable = 'foo'; };
// you do have access to the shared
// variables here if you need them.
}
// After the constructor, you set up the
// prototype, if any. This is an object of shared
// properties and methods to be inherited by every
// instance made by the constructor, and it also
// inherits the prototype's prototype, too.
// Lets use a literal object for simplicity.
ConstructedObject.prototype = {
// Accessing the instance to which a method
// applies is done using the "this" keyword,
// similar to in the constructor
sharedMethod : function () { return [sharedVariable, this.instanceMethod(),this.instanceProperty]; },
changeSharedVar : function () { sharedVariable = 'bar'; }
// properties may also be defined
};
// Finally, the constructor is returned so it
// can be kept alive outside of the anonymous
// function used to create it
return ConstructedObject;
// and the anonymous function is called to execute
// what we've done so far
})();
执行上述代码后，您将拥有一个构造函数，该构造函数创建具有实例特定变量和共享变量的对象。现在让我们通过创建两个实例并在一些更改前后比较它们来看看它们的行为。
// First create the two instances
var myObjA = new ConstructedObject(),
myObjB = new ConstructedObject();
// Now compare them, the sharedMethod method we
// used in the prototype offers an easy way to
// do this
console.log( myObjA.sharedMethod(), myObjB.sharedMethod() );
// ["foo", "bar", true] ["foo", "bar", true]
// Next lets change the different variables in
// myObjB so we can see what happens, again the
// change* methods defined before let us do this
// easily
myObjB.changeInstanceVar();
myObjB.changeSharedVar();
// For completeness, lets also change the property
// on myObjB.
myObjB.instanceProperty = false;
// Now when we compare them again, we see that our
// changes to the myObjB instance have only changed
// the shared variables of myObjA
console.log( myObjA.sharedMethod(), myObjB.sharedMethod() );
// ["bar", "bar", true] ["bar", "foo", false]
这是两个记录的语句一起，以便于查看
// myObjA myObjB
["foo", "bar", true] ["foo", "bar", true]
["bar", "bar", true] ["bar", "foo", false]