asp.net DROPDOWNLIST有条件回传 [英] asp.net Dropdownlist conditional postback

问题描述

我有一个DropDownList，并有一个事件的SelectedIndexChanged这postsback，我希望能够表现出一个消息时，他改变的DropDownList值用户的基础上，从信息输入，如果我不得不回传我会决定还是不行。

表示将你确定的消息？如果他选择是的，我将继续与回传，如果他说没有，我会取消，回传和选择分配previous值。

我已经搜索了很多，但无法弄清楚解决这个

，我想如果有一个SCRIPT关闭决定是否需要或不回传，可以帮助我猜

感谢

解决方案

  //获取到的DropDownList参考
变种selectlistId ='＆下;％= ddlYourList.ClientID％GT;'，
    选择列表=的document.getElementById（selectlistId）;//附加到onchange事件
selectlist.onchange =功能（）{  //决定是否执行__doPostBack事件，该事件提交
  //形式回服务器
  如果（确认（你确定要这么做吗？））{
     __doPostBack（selectlistId，''）;
  }
};
 

I have a dropdownlist and have an event selectedIndexChanged which postsback, i want to be able to show a message to the user whenever he changes the value in dropdownlist, based on the input from the message i will decide if i have to postback or not.

The message shown would be are you sure? if he selects yes i would continue with postback, if he says no, i would cancel the postback and assign the previous value as selected.

I have searched alot but cant figure out a solution to this, i think if there is a javascipt function which determines if a postback is required or not that could help i guess

Thanks

解决方案

// get a reference to the DropDownList
var selectlistId = '<%= ddlYourList.ClientID %>',
    selectlist = document.getElementById(selectlistId);

// attach to the onchange event
selectlist.onchange = function() {

  // decide whether to execute the __doPostBack event, which submits the
  // form back to the server
  if(confirm("Are you sure you want to do this?")){
     __doPostBack(selectlistId, '');
  }
};

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