抽象是一种隐藏实现细节并仅向用户显示函数的方法。换句话说，它忽略了无关的细节，只显示了所需的细节。
要点
- 无法创建Abstract Class抽象类的实例。
- 它减少了代码的重复。
例子1
检查是否可以创建Abstract类的实例。
<script> //Creating a constructor function function Vehicle() { this.vehicleName= vehicleName; throw new Error("You cannot create an instance of Abstract class");} Vehicle.prototype.display=function() { return this.vehicleName; } var vehicle=new Vehicle(); </script>
例子2
看一个实现抽象的例子。
<script> //Creating a constructor function function Vehicle() { this.vehicleName="vehicleName"; throw new Error("You cannot create an instance of Abstract Class"); } Vehicle.prototype.display=function() { return "Vehicle is: "+this.vehicleName; } //Creating a constructor function function Bike(vehicleName) { this.vehicleName=vehicleName; } //Creating object without using the function constructor Bike.prototype=Object.create(Vehicle.prototype); var bike=new Bike("Honda"); document.writeln(bike.display());</script>
输出:
Vehicle is: Honda
例子3
在此示例中，使用instanceof运算符测试对象是否引用了相应的类。
<script> //Creating a constructor function function Vehicle() { this.vehicleName=vehicleName; throw new Error("You cannot create an instance of Abstract class"); } //Creating a constructor function function Bike(vehicleName) { this.vehicleName=vehicleName; } Bike.prototype=Object.create(Vehicle.prototype); var bike=new Bike("Honda"); document.writeln(bike instanceof Vehicle); document.writeln(bike instanceof Bike);</script>
输出:
true true
