JavaScript抽象

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CSS创投周刊

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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

<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。

复制代码

<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。

复制代码

<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>