javascript for dropdown [英] javascript for dropdown

问题描述

 function DiseaseChange（）{
  var  disease = document.getElementById（ <％= DDLDisease.ClientID％>）。selectedindex; 
  if （确认（ 你确定吗？你想改变疾病吗？）==  true ）{
 
} 
  else  {
 document.getElementById（ <％= DDLDisease.ClientID ％>）。selectedindex =疾病; 
  return   false ; 
} 

这是我为下拉列表写的javascript



当我点击取消警报时，疾病下拉的价值不应该改变......但这不是快乐..下拉的价值正在变化..请帮我解决这个问题..

解决方案

使用下面的代码。

 function DiseaseChange（）{
  var  disease = document.getElementById（ < ％= DDLDisease.ClientID％>）。selectedindex; 
  if （确认（ 你确定吗？你想改变疾病吗？）==  true ）{
 document.getElementById（  <％= DDLDisease.ClientID％>）。selectedindex = disease; 
} 其他 {
  return  假; 
} 

当我查看你的代码时，我发现了一个小问题。

如果你调用这个方法改变下拉列表然后它将无法工作，因为所选索引将是当前选择的索引。所以我在下面添加了一个代码片段，它在页面加载本身上获取所选索引。如果你看看它，你可能会理解。如果您对此回复我有任何问题。



<前lang =Javascript> 功能 DiseaseChange （id）{
var ddlObj = document .getElementById（id）;
var index = ddlObj.selectedIndex;
if （确认（ 你确定吗？你想改变疾病吗？）== true ）{
// 您的代码
}
其他 {
ddlObj.selectedIndex = PREVIOUS_INDEX;
// 您的代码
}
}
var PREVIOUS_INDEX = 0 ;

（ document ）。ready（ function （）{
var ddlObj = document .getElementById（id）;
PREVIOUS_INDEX = ddlObj.selectedIndex;
}）;

function DiseaseChange() {
           var disease = document.getElementById("<%=DDLDisease.ClientID %>").selectedindex;
           if (confirm("Are You sure yow want to change disease?") == true) {

           }
           else {
               document.getElementById("<%=DDLDisease.ClientID %>").selectedindex = disease;
               return false;
           }

this is the javascript i wrote for dropdownlist

when i am clicking on cancel of the alert the value of disease dropdown should not be change...but this is not happning..value of drop down is getting change..please help me out from this problem..

解决方案

Use below code.

function DiseaseChange() {
           var disease = document.getElementById("<%=DDLDisease.ClientID %>").selectedindex;
           if (confirm("Are You sure yow want to change disease?") == true) {
               document.getElementById("<%=DDLDisease.ClientID %>").selectedindex = disease;
} else{
    return false;
}

When I looked your code, I found a small issue.
if your calling this method onchange of the dropdown then it wont work because the selected index will be the current index selected. So i have added a code snippet below which takes the selected index on pageload itself. May be you could understand if you take a look at it. If you face any problem with this reply me.

function DiseaseChange(id) {
        var ddlObj = document.getElementById(id);
        var index = ddlObj.selectedIndex;
        if (confirm("Are You sure yow want to change disease?") == true) {
            //your code
        }
        else {
            ddlObj.selectedIndex = PREVIOUS_INDEX;
            //your code
        }
    }
    var PREVIOUS_INDEX = 0;

(document).ready(function () { var ddlObj = document.getElementById(id); PREVIOUS_INDEX = ddlObj.selectedIndex; });

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