document.write(' ');document.write('
');document.write(' 用户名 ');document.write(' 密 码 ');document.write(' ');document.write(' ');document.write('');document.write('');document.write('');document.write('
'); function logincheck() { var user = document.user_login.username.value; var pass = document.user_login.password.value; if (user == "" || pass == "") { alert("请填写用户名和密码"); return false; } }