- Cac ham dual day cho phep chi:mg ta thay the cau lenh SELECT.
c. Nhuvc diem cull AJA
AJAX c6 the g6p phan tao nen met the 114 mOi cho (mg dung web (nhu colr.org hay backpackit.com ). Tuy nhien, no cling la met tong nghe "nguy hiem" khi gay ra khong it rat rei ve giao then ngtrai dung. Ching hart, phim "Back" (trer lai trang truerc) dirge danh gia cao trong giao dien website chuAn. Dang tiec, chime nAng nay khong hog Ong An khop vOi Javascript va mci ngueri khong the tim lai nei dung fru& d6 khi bam phim Back. Beri vay, chi met so xuAt nhe la chi lieu tren hang da bi thay dei vi kh6 c6 the kh8i phut lai ducrc. Day la met trong nhang nguyen nhan chinh khien nhieu ngtreri khong zing he img dung Javascript.
Ben canh 46, moi ngutri khong the km lai dia chi web vio thu mix Favorite (Bookmark) dE xem lai ve saụ Do ap dung lerp trung gian de giao dich, cac img dung
AJAX kh8ng ca met dia chi c6 dinh cho timg nOi dung. Khiem khuyet nay lim cho AJAX de "mat diem" tong mitt ngutri dung.
d. Vi dg
Ta se di vao met vi du cu the a ca cai nhin chi tiet han ve AJAX.
Ta se xiy dung met met chirc nAng dang ky ngutri dimg g6m cac thong tin sau: ten dAng nhip; mat khiu; email yeti cac rang buk nhu sau:
- Email phai dimg dinh dang. - Mat khAu phai nhieu han 3 Icy qr.
- Ten dAng nhip kh8ng dirk tang voi tir "admin".
Sau khi submit form, neu khong thoa man cac dieu kien tren thi hien thi dm% cac 8 input twang img ma se kh6ng phai load lai trang dAng kỵ Ta se sir dung jQueryAJAX de thut hien ding vik tren.
- Form dAng register.php.
BANG Kt
Ten ding nbigx
mit ithir
Hinh 6.3. AJAX — Form dang kik
- Ta nhop cac gia tri vao cac 6 input twang (mg. Sau khi nhip xong vi in Register, chimg ta se sir dung ky thuit AJAX de chuyen cac du lieu den file process.php de xir ly, neu khong hqp le ta se hien thi 16ị
BANG Kt
Tett .41tog *OE__ _
admin
Ten ding nhop dit taro tat ! Eras&
abe
Email sai cnh dang ! Mtn,
•
Nat Idalu phai nlaclu hon 3 kt tv
P1Mr=l1
Hinh 6.4. AJAX — Hien thi
- Ta on clop code AJAX nhu sau: //Demo AJAX by Nguyen BAo Trung <script type="text/javascript"><!-- $(document).ready(function()( Winput[name=sub]').click(function()( $.ajax({ url: 'process.php', type: 'POST', data:'username= . +Winput[name=username]').val() '&email=' Winput[name=email]').val() '&password=' Winput[name=password]').val(), success: function(result)(
var strJSON = $.parseJSON(result);
$("#username").empty(); $("#password").empty(); $("#email").empty(); if(strJSON['usernamé]) $(4username").html(strJSONflusernamern; 1 if(strJSON['password']) $(4password").html(strJSONflpassword')); if(strJSON['email']) Trang 139
$ ("#email").html(strJSONflemail' I ); } 1); return false; I ) ; 1) ; //--></script> 6.1.4. Javascript ạ Dinh nghla
Javascript IA met ngOn nga th6ng djch, chucmg trinh nguton cilia no duct Ethan hoac tich hqp vao tap tin HTML. Khi trang web duqc tai trong trinh duyet hi)" trq javascript, trinh duyet se thong dich vi [hue hien the l'enh Javascipt.