Facebook没有JS？

Question

Facebook的移动版本允许网站在没有JavaScript的情况下运行.

我在Chrome Android浏览器上禁用了JS.

当我尝试对帖子发表评论时,POST按钮最初为灰色并禁用; 但是,当我输入任何内容时,它会变为蓝色并变为启用状态.

没有JS,这怎么可能？

Answer 1

HTML5验证和CSS

input:invalid {
  background-color: #ffdddd;
}

form:invalid [type="submit"] {
  background-color: #CCC;
  color: #AAA;
}

<form>
  <label>Enter a Name</label>
  <input type="text" required/>
  <br />
  <br />
  <label>Enter an email address:</label>
  <input type="email" required/>
  
  <input type="submit" />
</form>


----------

如果要禁用它,可以使用两个按钮并切换显示

input:invalid {
  background-color: #ffdddd;
}

form [type="submit"][disabled] {
    display: none;
}

form:invalid [type="submit"][disabled] {
    display: inline;
}


form:invalid [type="submit"] {
  display: none;
}

<form>
  <label>Enter a Name</label>
  <input type="text" required/>
  <br />
  <br />
  <label>Enter an email address:</label>
  <input type="email" required/>
  
  <input type="submit" />
  <input type="submit" disabled="disabled" />
</form>