如何根据另一个下拉列表中的选择选择下拉列表中的选项

How to select an option in a dropdown list based on a selection in another dropdown list(如何根据另一个下拉列表中的选择选择下拉列表中的选项)

问题描述

我有两个已经从数据库填充的下拉列表.如果您在 DropDownlist1 中选择一个值 - Dropdownlist2 获得与 Dropdownlist1 中选择的值相同的值.

I have two DropDown lists which are already populated from the database. If you select a value in DropDownlist1 - Dropdownlist2 gets the same value that was selected in Dropdownlist1.

但是代码是基于 switch case 的，而且选项也是硬编码的！将来 - 可能会出现许多选项，但它不会起作用！

But the code is based on switch case and also the options are hard coded ! In future - Many options might spring up and it will not work !

所以我想要的是如果您在下拉列表 1 中选择一个选项 - 应根据值"而不是索引"在下拉列表 2 中选择该选项 喜欢这里

So what I want is If you select an option in Dropdown list 1 - The option should be selected in DropDown list 2 based on the "value" and not "index" Like here

任何指示或帮助将不胜感激！提前致谢

Any pointers or help would be appreciated ! Thanks in advance

 function showSelected(f) {

var selNum  = f.type1.selectedIndex;
//var selText = f.type1.options[selNum].text


switch (selNum)
{
case 1:
document.getElementById('type2').selectedIndex= 2;
break;

case 2:
document.getElementById('type2').selectedIndex = 8;
break;

case 3:
document.getElementById('type2').selectedIndex = 3;
break;

case 4:
document.getElementById('type2').selectedIndex = 1;
break;

case 5:
document.getElementById('type2').selectedIndex = 4;
break;

case 6:
document.getElementById('type2').selectedIndex = 2;
break;

case 7:
document.getElementById('type2').selectedIndex = 2;
break;

case 8:
document.getElementById('type2').selectedIndex = 7;
break;

}


}

 <select name="Type1" id="Type1" onchange="showSelected(this.form)" >
<option>Select Option</option>
    <option  value="<?php echo $record->getID();?>" > <?php echo $record->getIDName();?> </option>
 </select>       

 <select name="Type2" id="Type2" disabled>
<option>Select Option</option>
    <option  value="<?php echo $record->getID();?>" ><?php echo $record->getIDValue();?> </option>
 </select>     

推荐答案

function selectoption()
    {
        var list = document.getElementById('list');
        var listtwo = document.getElementById('listtwo');
        var searchtext = list.options[list.selectedIndex].text; 
        for(var i = 0; i < listtwo.options.length; ++i)
            if (listtwo.options[i].text === searchtext) listtwo.options[i].selected = true;
    }

http://jsbin.com/oyaloc/2

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