javascript 原型 - 如何从下拉列表中取消选择选定的值
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Prototype - How to deselect the selected value from a dropdown
提问by woot586
How do I deselect the selected value from a dropdown list using Prototype.
如何使用 Prototype 从下拉列表中取消选择选定的值。
From
从
<select id=“mylist” MULTIPLE >
<option value=“val-1”>Value 1</option>
<option value=“val-2” SELECTED>Value 2</option>
<option value=“val-3”>Value 3</option>
</select>
To
到
<select id=“mylist” MULTIPLE >
<option value=“val-1”>Value 1</option>
<option value=“val-2”>Value 2</option>
<option value=“val-3”>Value 3</option>
</select>
Thanks for any help in advance.
提前感谢您的任何帮助。
采纳答案by woot586
I found the following code worked well:
我发现以下代码运行良好：
var options = $$('select#mylist option');
var len = options.length;
for (var i = 0; i < len; i++) {
options[i].selected = false;
}
回答by kzh
I'm not sure how to do it in prototype, but I can do it in JavaScript.
我不确定如何在原型中做到这一点，但我可以在 JavaScript 中做到这一点。
For a regular select, set yourSelectElement.selectedIndex = -1.
对于常规选择，设置yourSelectElement.selectedIndex = -1.
For a multiple select, you can just ctrl+clickon the selected item, but you can do it programmatically as well. See link.
对于多选，您可以只在所选项目上加ctrl+ click，但您也可以通过编程方式进行。见链接。
回答by remi bourgarel
You can't : you'll have to add an empty option
你不能：你必须添加一个空选项
<option></option>
and then
接着
$$("#mylist option[selected]")[0].selected = false;
$$("#mylist option")[0].selected = true;
回答by clockworkgeek
On the event of the second list being selected...
在选择第二个列表的事件...
Event.observe('secondlist', 'change', function(){
if (this.selectedIndex >= 0)
$$('#mylist option[selected]').invoke('writeAttribute', 'selected', false);
});
