AJAX and ASP
ASP - AJAX and ASP
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AJAX is used to create more interactive applications.
AJAX ASP Example
The following example will demonstrate how a web page can communicate with a
web server while a user type characters in an input field:
Example
Start typing a name in the input field below:
Suggestions:
Try it yourself »
Example Explained - The HTML Page
When a user types a character in the input field above, the function "showHint()" is executed. The function is triggered by the "onkeyup"
event:
<!DOCTYPE html>
<html>
<head>
<script>
function showHint(str)
{
if (str.length==0)
{
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 (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("txtHint").innerHTML=xmlhttp.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)" size="20">
</form>
<p>Suggestions: <span id="txtHint"></span></p>
</body>
</html>
Source code explanation:
If the input field is empty (str.length==0), the function clears the
content of the txtHint placeholder and exits the function.
If the input field is not empty, the showHint() function executes the following:
Notice that a parameter (q) is added to the URL (with the content of the
input field)
The ASP File
The page on the server called by the JavaScript above is an ASP file called "gethint.asp".
The source code in "gethint.asp" checks an array of names, and returns the corresponding name(s) to the
browser:
<%
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
%>
Explanation: If there is any text sent from the JavaScript (strlen($q) > 0), the following happens:
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