ASP AJAX
AJAX — butun sahifani qayta yuklamasdan veb-sahifaning ayrim qismlarini yangilash demakdir.
AJAX nima?
AJAX = Asynchronous JavaScript and XML (asinxron JavaScript va XML).
AJAX — tez va dinamik veb-sahifalar yaratish texnikasi.
AJAX parda ortida server bilan kichik hajmdagi ma’lumotlar almashish orqali veb-sahifalarni asinxron yangilash imkonini beradi. Bu butun sahifani qayta yuklamasdan veb-sahifaning ayrim qismlarini yangilash mumkinligini anglatadi.
Klassik veb-sahifalar (AJAX ishlatmaydiganlar) mazmun o‘zgarishi kerak bo‘lsa, butun sahifani qayta yuklashi kerak.
AJAX’dan foydalanadigan ilovalarga misollar: Google Maps, Gmail, Youtube va Facebook tablari.
AJAX qanday ishlaydi
AJAX internet standartlariga asoslanadi
AJAX internet standartlariga asoslanadi va quyidagilarning kombinatsiyasidan foydalanadi:
- XMLHttpRequest obyekti (server bilan asinxron ma’lumot almashish uchun)
- JavaScript/DOM (ma’lumotlarni ko‘rsatish va ular bilan ishlash uchun)
- CSS (ma’lumotlarga uslub berish uchun)
- XML (ko‘pincha ma’lumot uzatish formati sifatida ishlatiladi)
AJAX ilovalari brauzer va platformaga bog‘liq emas!
Google Suggest
AJAX 2005-yilda Google tomonidan Google Suggest orqali ommalashdi.
Google Suggest juda dinamik veb-interfeys yaratish uchun AJAX’dan foydalanadi: Google qidiruv maydoniga yoza boshlaganingizda, JavaScript harflarni serverga yuboradi va server takliflar ro‘yxatini qaytaradi.
AJAX’dan bugunoq foydalanishni boshlang
ASP darsligimizda AJAX butun sahifani qayta yuklamasdan veb-sahifaning ayrim qismlarini qanday yangilashini ko‘rsatamiz. Server skripti ASP’da yoziladi.
AJAX haqida ko‘proq bilmoqchi bo‘lsangiz, AJAX darsligimizga tashrif buyuring.
AJAX ASP misoli
Quyidagi misol foydalanuvchi kiritish maydoniga belgilar yozayotganda veb-sahifa veb-server bilan qanday aloqa qila olishini ko‘rsatadi:
Misol
Start typing a name in the input field below:
Suggestions:
Misol izohi
Yuqoridagi misolda foydalanuvchi kiritish maydoniga belgi yozganda "showHint()" nomli funksiya bajariladi.
Funksiya onkeyup hodisasi orqali ishga tushadi.
Mana HTML kodi:
Misol
<html>
<head>
<script>
function showHint(str) {
if (str.length == 0) {
document.getElementById("txtHint").innerHTML = "";
return;
} else {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
document.getElementById("txtHint").innerHTML = this.responseText;
}
};
xmlhttp.open("GET", "gethint.asp?q=" + str, true);
xmlhttp.send();
}
}
</script>
</head>
<body>
<p><b>Start typing a name in the input field below:</b></p>
<form>
First name: <input type="text" onkeyup="showHint(this.value)">
</form>
<p>Suggestions: <span id="txtHint"></span></p>
</body>
</html>
O‘zingiz sinab ko‘ring »
Kod tushuntirishi:
Avval kiritish maydoni bo‘shligini tekshiring (str.length == 0). Agar bo‘sh bo‘lsa, txtHint joy egasining mazmunini tozalang va funksiyadan chiqing.
Biroq kiritish maydoni bo‘sh bo‘lmasa, quyidagilarni bajaring:
- XMLHttpRequest obyektini yaratish
- Server javobi tayyor bo‘lganda bajariladigan funksiyani yaratish
- So‘rovni serverdagi ASP fayliga (gethint.asp) yuborish
- E’tibor bering, q parametri qo‘shiladi: gethint.asp?q="+str
- str o‘zgaruvchisi kiritish maydonining mazmunini saqlaydi
ASP fayli - "gethint.asp"
ASP fayli ismlar massivini tekshiradi va mos keladigan ism(lar)ni brauzerga qaytaradi:
<%
response.expires=-1
dim a(30)
'Fill up array with names
a(1)="Anna"
a(2)="Brittany"
a(3)="Cinderella"
a(4)="Diana"
a(5)="Eva"
a(6)="Fiona"
a(7)="Gunda"
a(8)="Hege"
a(9)="Inga"
a(10)="Johanna"
a(11)="Kitty"
a(12)="Linda"
a(13)="Nina"
a(14)="Ophelia"
a(15)="Petunia"
a(16)="Amanda"
a(17)="Raquel"
a(18)="Cindy"
a(19)="Doris"
a(20)="Eve"
a(21)="Evita"
a(22)="Sunniva"
a(23)="Tove"
a(24)="Unni"
a(25)="Violet"
a(26)="Liza"
a(27)="Elizabeth"
a(28)="Ellen"
a(29)="Wenche"
a(30)="Vicky"
'get the q parameter from URL
q=ucase(request.querystring("q"))
'lookup all hints from array if length of q>0
if len(q)>0 then
hint=""
for i=1 to 30
if q=ucase(mid(a(i),1,len(q))) then
if hint="" then
hint=a(i)
else
hint=hint & " , " & a(i)
end if
end if
next
end if
'Output "no suggestion" if no hint were found
'or output the correct values
if hint="" then
response.write("no suggestion")
else
response.write(hint)
end if
%>
AJAX ma’lumotlar bazasi bilan interaktiv aloqa uchun ishlatilishi mumkin.
AJAX ma’lumotlar bazasi misoli
Quyidagi misol veb-sahifa AJAX yordamida ma’lumotlar bazasidan qanday ma’lumot olishi mumkinligini ko‘rsatadi:
Misol tushuntirishi - HTML sahifa
Foydalanuvchi yuqoridagi ochiladigan ro‘yxatdan mijozni tanlaganda "showCustomer()" nomli funksiya bajariladi. Funksiya "onchange" hodisasi orqali ishga tushadi:
<!DOCTYPE html>
<html>
<head>
<script>
function showCustomer(str)
{
if (str=="")
{
document.getElementById("txtHint").innerHTML="";
return;
}
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (this.readyState==4 && this.status==200)
{
document.getElementById("txtHint").innerHTML=this.responseText;
}
}
xmlhttp.open("GET","getcustomer.asp?q="+str,true);
xmlhttp.send();
}
</script>
</head
<body>
<form>
<select name="customers" onchange="showCustomer(this.value)">
<option value="">Select a customer:</option>
<option value="ALFKI">Alfreds Futterkiste</option>
<option value="NORTS ">North/South</option>
<option value="WOLZA">Wolski Zajazd</option>
</select>
</form>
<
<div id="txtHint">Customer info will be listed here...</div>
</body>
</html>
Manba kod tushuntirishi:
Agar hech qanday mijoz tanlanmagan bo‘lsa (str.length==0), funksiya txtHint joy egasining mazmunini tozalaydi va funksiyadan chiqadi.
Agar mijoz tanlangan bo‘lsa, showCustomer() funksiyasi quyidagilarni bajaradi:
- XMLHttpRequest obyektini yaratish
- Server javobi tayyor bo‘lganda bajariladigan funksiyani yaratish
- So‘rovni serverdagi faylga yuborish
- E’tibor bering, URL’ga (ochiladigan ro‘yxat mazmuni bilan) parametr (q) qo‘shiladi
ASP fayli
Yuqoridagi JavaScript chaqiradigan serverdagi sahifa — "getcustomer.asp" nomli ASP fayli.
"getcustomer.asp" faylidagi manba kod ma’lumotlar bazasiga so‘rov yuboradi va natijani HTML jadvalda qaytaradi:
<%
response.expires=-1
sql="SELECT * FROM CUSTOMERS WHERE CUSTOMERID="
sql=sql & "'" & request.querystring("q") & "'"
set conn=Server.CreateObject("ADODB.Connection")
conn.Provider="Microsoft.Jet.OLEDB.4.0"
conn.Open(Server.Mappath("/datafolder/northwind.mdb"))
set rs=Server.CreateObject("ADODB.recordset")
rs.Open sql,conn
response.write("<table>")
do until rs.EOF
for each x in rs.Fields
response.write("<tr><td><b>" & x.name & "</b></td>")
response.write("<td>" & x.value & "</td></tr>")
next
rs.MoveNext
loop
response.write("</table>")
%>
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