我在更改下面代码中的选项值时遇到问题，选择哪些更改取决于其他选择，但我想更改选择 id =“numbList”的值，谢谢....
<!DOCTYPE html>
<html>
<body>
<select id="diffList" onchange="changeList()">
<option value="">-- Difficulty --</option>
<option value="1">Easy</option>
<option value="2">Medium</option>
<option value="3">Difficult</option>
</select>
<select id="numbList"></select>
<script>
window.difficulty = {};
window.difficulty['1'] = [1,2,3];
window.difficulty['2'] = [4,5,6];
window.difficulty['3'] = [7,8,9];
function changeList() {
var diffList = document.getElementById("diffList");
var numbRange = document.getElementById("numbList");
var selectDiff = diffList.options[diffList.selectedIndex].value;
while(numbRange.options.length)
{
numbRange.remove(0);
}
var diff = window.difficulty[selectDiff];
if(diff)
{
var i;
for(i = 0; i < diff.length; i++)
{
var difficulty = new Option(diff[i], i);
numbRange.options.add(difficulty);
}
}
}
</script>
</body>
</html>
最佳答案
只需使用 diff[i] 作为选项的文本和值:
...
for(i = 0; i < diff.length; i++)
{
var value = diff[i];
var difficulty = new Option(value, value);
numbRange.options.add(difficulty);
}
...
当先前的值从选择选项中删除时，它会选择第一个新选项。所以你不需要设置 numbList 的值。
要以编程方式设置 numbList 的值，您只需执行 numbList.value = 1; 即可。
关于javascript - 根据另一个选定的下拉列表更改下拉列表中的选项值，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37956410/