HTML5占位符jQuery插件 演示与范例 用法示例 HTML < input type =" text " name =" name " placeholder =" e.g. John Doe " > < input type =" email " name =" email " placeholder =" e.g. address@example.ext " > < input type =" url " name =" url " placeholder =" e.g. https://mathiasbynens.be/ " > < in