ES6 handler.construct()用法及代码示例

下面的例子定义了一个类Student带有一个构造函数和一个 getter 方法。构造函数将 firstName 和 lastName 作为参数。该程序创建一个代理并定义一个处理程序对象来拦截构造函数。处理程序对象验证传递给构造函数的参数数量。如果正好有两个参数没有传递给构造函数，处理程序对象就会抛出错误。

<script>
   class Student{
      constructor(firstName,lastName){
         this.firstName = firstName
         this.lastName = lastName
      }
   
      get fullName(){
         return `${this.firstName}:${this.lastName}`
      }
   }
   const handler = {
      construct:function(target,args){

         if(args.length==2) {
            return Reflect.construct(target,args);
         }
         else throw 'Please enter First name and Last name'
      }
   }
   const StudentProxy = new Proxy(Student,handler)
   const s1 = new StudentProxy('kannan','sudhakaran')
   console.log(s1.fullName)
   const s2 = new StudentProxy('Tutorials')
   console.log(s2.fullName)
</script>

上面代码的输出将如下所示：

kannan:sudhakaran
Uncaught Please enter First name and Last name