blocks|key|159016|text|请使用以下内容|type|unstyled|depth|inlineStyleRanges|entityRanges|data|159017|<option+value="">Choose</option>|code-block|syntax|javascript|159018|将上述系列追加为第一个选项|159019|159020|被认为有效，因为第一个子元素没有内容。|unordered-list-item|159021|159022|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Q|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|R|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|S|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|T|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|U|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|O|$]]

Use the following 

<pre><code>&lt;option value=""&gt;Choose&lt;/option&gt;
</code></pre>

Append the above series as first option

<ul>
<li>considered valid as the first child element has no content.</li>
</ul>

blocks|key|161454|text|有时你真的只想有一个空白的选项。您过去只能插入一个空格，w3c验证器会接受它。这在过去是有效的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|161455|<option+value="">+</option>|code-block|syntax|javascript|161456|现在看来，您必须使用不间断的空格来传递验证器：|161457|<option+value="">&nbsp;</option>|161458|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Sometimes you really just want to have a blank option. You used to be able to just insert a single space and the w3c validator would accept it. This used to work:

<pre><code>&lt;option value=""&gt; &lt;/option&gt;
</code></pre>

Now it seems you must use a non-breaking space to pass the validator:

<pre><code>&lt;option value=""&gt;&amp;nbsp;&lt;/option&gt;
</code></pre>

blocks|key|2964821|text|这里是W3C+HTML+Checker+(也称为验证器)的维护者。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2964822|2964823|现在看来，您必须使用不间断的空格来传递验证器：|blockquote|2964824|2964825|<option+value="">&nbsp;</option>|offset|length|style|CODE|2964826|2964827|是啊，我不太确定我什么时候在收银台改的。我认为我在这几年中没有做任何更改，但不管怎样，检查器在这方面符合超文本标记语言规范，因为如果您转到https://html.spec.whatwg.org/multipage/forms.html#the-option-element并阅读该部分标题中的内容模型小节，您将看到：|BOLD|2964828|如果元素没有标签属性，则为|2964829|：不是元素间空格的文本。|2964830|2964831|2964832|2964833|换言之，超文本标记语言本质上将不间断的空格字符视为文本，而不是空格字符，因此将其放入option元素中将使option元素成为“非空”(就规范而言)。|2964834|因此，执行<option+value="">&nbsp;</option>并不是一种真正的技巧；相反，它是使option非空的一种完全合理的方法(同样，就规范而言)。|2964835|entityMap|0|LINK|mutability|MUTABLE|url|https://html.spec.whatwg.org/multipage/forms.html#the-option-element^0|0|0|0|0|0|W|0|0|43|4|1X|1W|0|0|0|0|0|0|0|16|6|1H|6|0|5|W|1I|6|0^^$0|@$1|2|3|4|5|6|7|19|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|1B|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|1D|8|@$I|1E|J|1F|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|1H|8|@$I|1I|J|1J|K|P]]|9|@$I|1K|J|1L|1|1M]]|A|$]]|$1|Q|3|R|5|6|7|1N|8|@]|9|@]|A|$]]|$1|S|3|T|5|E|7|1O|8|@]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]|$1|V|3|-4|5|6|7|1Q|8|@]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1R|8|@]|9|@]|A|$]]|$1|X|3|Y|5|6|7|1S|8|@$I|1T|J|1U|K|L]|$I|1V|J|1W|K|L]]|9|@]|A|$]]|$1|Z|3|10|5|6|7|1X|8|@$I|1Y|J|1Z|K|L]|$I|20|J|21|K|L]]|9|@]|A|$]]|$1|11|3|-4|5|6|7|22|8|@]|9|@]|A|$]]]|12|$13|$5|14|15|16|A|$17|18]]]]

Maintainer of the W3C HTML Checker (aka validator) here.

<blockquote>
 Now it seems you must use a non-breaking space to pass the validator:
 
 <code>&lt;option value=""&gt;&amp;nbsp;&lt;/option&gt;</code>
</blockquote>

Yeah I’m not sure when I changed that in the checker. I thought I hadn’t changed anything there in a couple of years but regardless, the checker is conforming to the HTML spec on this, because if you go to <a href="https://html.spec.whatwg.org/multipage/forms.html#the-option-element">https://html.spec.whatwg.org/multipage/forms.html#the-option-element</a> and read the Content model subsection in the head of that section, you’ll see:

<blockquote>
 If the element has no label attribute: Text that is not inter-element whitespace.
</blockquote>

In HTML, the <a href="https://html.spec.whatwg.org/multipage/infrastructure.html#space-character">definition of which characters can be <code>inter-element whitespace</code> characters</a> includes just U+0020 (space), tab, U+000A (LF), U+000C FORM FEED, and U+000D (CR).

In other words, HTML essentially considers the non-breaking space character to be Text—not a space character—so putting it inside an <code>option</code> element makes that <code>option</code> element “non-empty” (as far as the spec is concerned).

So, doing <code>&lt;option value=""&gt;&amp;nbsp;&lt;/option&gt;</code> isn’t really a hack; instead, it’s a perfectly reasonable way (again, as far as the spec is concerned) to make an <code>option</code> non-empty.

Using the following code on <code>select</code>:
<pre class="lang-html prettyprint-override"><code> &lt;select name=&quot;province&quot; id=&quot;province&quot; required=&quot;required&quot;&gt; 
 &lt;optgroup label=&quot;Provinces&quot;&gt;
 &lt;option value=&quot;Alberta&quot;&gt;Alberta&lt;/option&gt;
 &lt;option value=&quot;British Colombia&quot;&gt;British Colombia&lt;/option&gt;
 &lt;option value=&quot;Manitoba&quot;&gt;Manitoba&lt;/option&gt;
 &lt;option value=&quot;New Brunswick&quot;&gt;New Brunswick&lt;/option&gt;
 &lt;option value=&quot;Newfoundland and Labrador&quot;&gt;Newfoundland and Labrador&lt;/option&gt;
 &lt;option value=&quot;Nova Scotia&quot;&gt;Nova Scotia&lt;/option&gt;
 &lt;option value=&quot;Ontario&quot; selected=&quot;selected&quot;&gt;Ontario&lt;/option&gt;
 &lt;option value=&quot;Prince Edward Island&quot;&gt;Prince Edward Island&lt;/option&gt;
 &lt;option value=&quot;Quebec&quot;&gt;Quebec&lt;/option&gt;
 &lt;option value=&quot;Saskatchewan&quot;&gt;Saskatchewan&lt;/option&gt;
 &lt;/optgroup&gt;
 &lt;optgroup label=&quot;Territories&quot;&gt;
 &lt;option value=&quot;Northwest Territories&quot;&gt;Northwest Territories&lt;/option&gt;
 &lt;option value=&quot;Nunavut&quot;&gt;Nunavut&lt;/option&gt;
 &lt;option value=&quot;Yukon&quot;&gt;Yukon&lt;/option&gt;
 &lt;/optgroup&gt;
 &lt;/select&gt; 
</code></pre>
I need to have values same as the options its just required by guidelines. This code works fine but doesn't pass the W3C validation:
<blockquote>
A <code>select</code> element with a <code>required</code> attribute and without a <code>multiple</code> attribute, and whose size is 1, must have a child <code>option</code> element.
</blockquote>
What would be the solution to this problem?

HTML5 Validation error with select required attribute

在select上使用以下代码 <select name="province" id="province" required="required"> <optgroup label="Provinces"> <option value="Alberta">Alberta</o...

问选择必需属性时出现HTML5验证错误
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