JavaScript设计模式之职责链模式应用示例

/
 @param: orderType 表示订单类型
 @param: pay 表示用户是否已经支付定金
 @param: stock 表示当前用户普通购买的手机库存数量，交过定金的用户不受此限制
/
var order500 = function( orderType, pay, stock ){
  if( orderType === 1 && pay === true)
     console.log('500元定金预购，得到100优惠卷');
  else
     return 'nextSuessor'; //不知道下一个节点是谁，反正把请求往后面传递
};
var order200 = function( orderType, pay, stock){
  if( orderType === 2 && pay === true)
    console.log( '200元定金预购，得到50元优惠卷' );
  else
    return 'nextSuessor';
};
var orderNormal = function(orderType, pay, stock){
  if(stock > 0)
    console.log('普通购买，无优惠卷');
  else
    console.log('手机库存不足');
};

var Chain = function(fn){
  this.fn = fn;
  this.suessor = null;
};
Chain.prototype.setNextSuessor = function( suessor ){
  return this.suessor = suessor;
};
Chain.prototype.passRequest = function(){
  var ret = this.fn.apply( this, arguments );
  if( ret === 'nextSuessor'){
    return this.suessor && this.suessor.passRequest.apply( this,suessor, arguments );
  }
   return ret;
};

var chainOrder500 = new Chain( order500 );
var chainOrder200 = new Chain( order200 );
var chainOrderNormal = new Chain( orderNormal );

chainOrder500.setNextSuessor( chainOrder200 );
chainOrder200.setNextSuessor( chainOrderNormal );

chainOrder500.passRequest( 1, true, 500 ); //输出500元定金预购，得到100优惠卷
chainOrder500.passRequest( 2, true, 500 ); //输出200元定金预购，得到50优惠卷
chainOrder500.passRequest( 3, true, 500 ); //输出普通购买，无优惠卷
chainOrder500.passRequest( 1, false, 0 ); //输出手机库存不足