The W3C Markup Validation Service

The checked attribute is a boolean attribute. When present, it specifies that an <input> element should be pre-selected (checked) when the page ...

方法. 透過 .form-check 瀏覽器的預設核取方塊和選項按鈕獲得替代，藉由一系列的class 來改進這兩種輸入類型的HTML 元素的排版和行為，並提供更好的自定義功能與跨瀏覽器 ...

<input> elements of type checkbox are rendered by default as boxes that are checked (ticked) when activated, like you might see in an official government paper ...

checkbox 类型的 <input> 元素在默认情况下被呈现为激活时被选中（打勾）的方框，就像你在官方的政府文件表格中看到的那样。具体外观取决于浏览器运行的 ... 尝试一下 · 其他属性 · 使用复选框输入 · 示例

This validator checks the markup validity of Web documents in HTML, XHTML, SMIL, MathML, etc. If you wish to validate specific content such as RSS/Atom feeds ...

Validates HTML files for compliance against the W3C standards and performs linting to assess code quality against best practices.

HTML Validator is an online HTML checker tool that checks HTML documents to ensure they follow the World Wide Web Consortium (W3C) rules.

定义和用法. checked 属性规定在页面加载时应该预先选定input 元素。 checked 属性是一个布尔属性。 如果已设置此属性，它指定在页面加载时应预选（选中）<input> 元素。