我可以将必需的属性应用于< select> HTML5中的字段? [英] Can I apply the required attribute to <select> fields in HTML5?
问题描述
如何检查用户是否从HTML5中的< select>
字段中选择了某些内容?
我看到< select>
不支持新的所需的
属性...我必须使用JavaScript然后?还是有什么我想念的? :::第一个值为空 - 必需的值为空值
先决条件:正确的html5 DOCTYPE和一个指定的输入字段
< select name =somenamerequired>
< option value =>请选择< / option>
< option value =one>一个< / option>
< / select>
根据文档(列表和粗体是我的)
必需属性是布尔
属性。
指定后,用户
将需要选择一个值
在提交表单之前。
如果选择元素
- 具有必需属性指定
- 没有指定multiple属性,
- 并且显示大小为1(不具有SIZE = 2或更多 - 省略它如果不需要);
- 如果
中第一个选项元素的值
选择元素的选项列表(如果
any)是空字符串(即value =),
- 和
选项元素的父节点是
选择元素(而不是optgroup
元素),
然后该选项是
select元素的占位符标签
选项。
How can I check if a user has selected something from a <select>
field in HTML5?
I see <select>
doesn't support the new required
attribute... do I have to use JavaScript then? Or is there something I’m missing? :/
Mandatory: Have the first value empty - required works on empty values
Prerequisites: correct html5 DOCTYPE and a named input field
<select name="somename" required>
<option value="">Please select</option>
<option value="one">One</option>
</select>
As per the documentation (the listing and bold is mine)
The required attribute is a boolean attribute.
When specified, the user will be required to select a value before submitting the form.If a select element
- has a required attribute specified,
- does not have a multiple attribute specified,
- and has a display size of 1 (do not have SIZE=2 or more - omit it if not needed);
- and if the value of the first option element in the select element's list of options (if any) is the empty string (i.e. present as
value=""
),- and that option element's parent node is the select element (and not an optgroup element),
then that option is the select element's placeholder label option.
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