职责链模式

JS

var  order500  =  function  (orderType,  pay,  stock)  {
    if  (orderType  ===  1  &&  pay  ===  true)  {
        console.log('500')
    }  else  {
        return  'nextSuccessor'  // 我也不知道下个节点是谁
    }
}


var  order200  =  function  (orderType,  pay,  stock)  {
    if  (orderType  ===  2  &&  pay  ===  true)  {
        console.log('200')
    }  else  {
        return  'nextSuccessor'  // 我也不知道下个节点是谁
    }
}


var  orderNormal  =  function  (orderType,  pay,  stock)  {
    if  (stock  >  0)  {
        console.log('普通购买，无优惠券')
    }  else  {
        console.log('手机库存不足');
    }
}


// 构造函数
var  Chain  =  function  (fn)  {
    this.fn  =  fn
    this.successor  =  null;
}


// 指定在链中的下一个节点
Chain.prototype.setNextSuccessor  =  function  (successor)  {
    return  this.successor  =  successor;
}


// 传递请求给某个节点
Chain.prototype.passRequest  =  function  ()  {
    var  ret  =  this.fn.apply(this,  arguments)
    if  (ret  ===  'nextSuccessor')  {
        return  this.successor  && this.successor.passRequest.apply(this.successor,  arguments)
    }
    return  ret
}


// AOE
Function.prototype.after  =  function  (fn)  {
    var  self  =  this;
    return  function  ()  {
    var  ret  =  self.apply(this,  arguments)
    if  (ret  ===  'nextSuccessor')  {
        return  fn.apply(this,  arguments)
    }
        return  ret
    }
}


var  order  =  order500.after(order200).after(orderNormal);
order(1,  true,  500);
order(2,  true,  500);
order(1,  false,  500);

输出