通过创建包装器<div>并添加.alert类和四个上下文类之一来添加基本警报，例如.alert-success，.alert-info，.alert-warning，.alert-danger。
您可以尝试运行以下代码来创建警报类-
<!DOCTYPE html> <html> <head> <title>Bootstrap Example</title> <link href = "/bootstrap/css/bootstrap.min.css" rel = "stylesheet"> <script src = "/scripts/jquery.min.js"></script> <script src = "/bootstrap/js/bootstrap.min.js"></script> </head> <body> <div class = "alert alert-success"> This is Success! </div> <div class = "alert alert-info"> This is Info! </div> <div class = "alert alert-warning"> This is Warning! </div> <div class = "alert alert-danger"> This is Error! </div> </body> </html>