<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <script type="text/javascript" src="http://mat1.gtimg.com/libs/jquery/1.12.0/jquery.js"></script> </head> <body> <form action="" method="post"> {% csrf_token %} 帐号: <input type="text" name="uname" onblur="f()" id="n" value="{{ a }}"> <span id="s"></span><br> 密码: <input type="text" name="pwd" value="{{ b }}"><br> <button>登录</button> <input type="checkbox" value="1" name="e">记住密码 </form> <script> function f() { var n = $('#n').val() if (n.length === 0) { $('#s').html('字段不能为空') $('#s').css('color', 'red') } else { $('#s').html('对') $('#s').css('color', 'blue') } } </script> </body> </html>