javascript - 将选择选项值设置为 null
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javascript - set select option value to null
提问by tanya
I have to disable all the selectmenus in a divand also set their value to null.
我必须禁用 a 中的所有select菜单div并将它们的值设置为null.
I am using the following code to disable the select menus:
我正在使用以下代码禁用选择菜单：
var div_contents =document.getElementById("div1");
var elements = div_contents.getElementsByTagName("select");
for (i=0; i<elements.length; i++) {
elements[i].disabled = true;
}
However, I am not able to set the value of the select tag to null.
但是，我无法将 select 标记的值设置为null.
Also I don't have the nulloption inside the selecttag:
我也没有标签null内的选项select：
<select id="test1" name="test1">
<option value="a">aa</option>
<option value="b">bb</option>
<option value="c">cc</option>
</select>
How can I set the value of a selectlist to null, given that I don't have the nulloption?
鉴于我没有选项，如何将select列表的值设置为？nullnull
回答by RightSaidFred
If you want to show no selection, you should set its selectedIndexto -1.
如果您不想显示任何选择，则应将其设置selectedIndex为-1。
elements[i].selectedIndex = -1;
回答by Blender
You could try setting the element's valueproperty:
您可以尝试设置元素的value属性：
elements[i].value = '';
