1. 职责链模式

将对象连成一条链，并沿着这条链传递请求，直到有一个对象处理它为止。

var chain = function(fn){

      this.fn = fn;

      this.successor = null;

}

chain.prototype.setNextSuccessor = function(successor){

      return this.successor = successor;

}

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;

}

var order200 = function(pay){

      if(pay){

             console.log('200');

      }else{

             return 'nextSuccessor';

      }

}

var normal = function(pay){

      if(pay){

             console.log('10');

      }else{

             console.log('50');

      }

}

var chain200 = new chain(order200);

var chainNormal = new chain(normal);

• order200.setNextSuccessor(chainNormal);

chain200.passRequest(false);