javascript设计模式 – 访问者模式原理与用法实例

var Keyboard = function(){
  this.aept = function(puterPartVisitor){
    puterPartVisitor.visit(this);
  }
}
 
var Monitor = function(){
  this.aept = function(puterPartVisitor){
    puterPartVisitor.visit(this);
  }
}
 
var Mouse = function(){
  this.aept = function(puterPartVisitor){
    puterPartVisitor.visit(this);
  }
}
 
var Computer = function(){
  var parts = [new Keyboard(), new Monitor(), new Mouse()];
 
  this.aept = function(puterPartVisitor){
    puterPartVisitor.visit(this);
    _aeptAll(puterPartVisitor);
  }
 
  var _aeptAll = function(puterPartVisitor){
    parts.map(function(item){
      item.aept(puterPartVisitor)
    });
  }
}
 
var ComputerPartDisplayVisitor = function(){
  this.visit = function(item){
    if(item.constructor == Keyboard){
      console.log("Displaying Keyboard.");
    }else if(item.constructor == Monitor){
      console.log("Displaying Monitor.");
    }else if(item.constructor == Mouse){
      console.log("Displaying Mouse.");
    }else if(item.constructor == Computer){
      console.log("Displaying Computer.");
    }else{
      console.log("Error");
    }
  }
}
 
var puter = new Computer();
puter.aept(new ComputerPartDisplayVisitor());
// Displaying Computer.
// Displaying Keyboard.
// Displaying Monitor.
// Displaying Mouse.