The String is formed by pairs of HTML Element (placeholder) Identifiers and the message-key that will be displayed inside that HTML element after resolution.
字符串由 HTML Element（占位符）Identifier 和消息键对组成，并且这个消息键将在解析之后显示在该 HTML 元素内。
2
Therefore, the entire element can contain any well-formed markup using any element or attribute names.
因此，整个元素可以包含使用任意元素和属性名称的任意格式良好的标记。
3
Remember, the DOM will create well-formed HTML, meaning that the element is currently empty, with both a starting and ending tag.