js文件上传前的预览和删除实例代码，具体如下： !DOCTYPE htmlhtml lang="en" head meta charset="UTF-8" / meta http-equiv="X-UA-Compatible" content="IE=edge" / meta name="viewport" content="width=device-width, initial-scale=1.0" / title文件上传预览和删除/title style #img-box{display: flex;