AJAX ASP/PHP Example

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AJAX is used to create more dynamic applications.

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AJAX ASP/PHP Examples

The following example will demonstrate how a web page communicates with a web server while a user types characters in an input field: Please type a letter (A - Z) in the input box below:

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Example Analysis - showHint() Function

When the user types a character in the input box above, the function "showHint()" is executed. This function is triggered by the "onkeyup" event:

Source code analysis:

If the input box is empty,str.length==0then the function clearstxtHintthe placeholder's content, and exits the function.

If the input box is not empty,showHint()the function performs the following tasks:

• CreateXMLHttpRequestobject
• Execute a function when the server response is ready
• Send the request to a file on the server
• Note that we added a parameter q (with the content of the input box) to the URL

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AJAX Server Page - ASP and PHP

The server page called by JavaScript in the above example is a PHP file namedgethint.php。

Below, we created two versions of the server file, one written in ASP and the other in PHP.

ASP File

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
%>

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PHP File

The following code is written in PHP and has the same effect as the ASP code above.

<?php
// Fill up array with names
$a[]="Anna";
$a[]="Brittany";
$a[]="Cinderella";
$a[]="Diana";
$a[]="Eva";
$a[]="Fiona";
$a[]="Gunda";
$a[]="Hege";
$a[]="Inga";
$a[]="Johanna";
$a[]="Kitty";
$a[]="Linda";
$a[]="Nina";
$a[]="Ophelia";
$a[]="Petunia";
$a[]="Amanda";
$a[]="Raquel";
$a[]="Cindy";
$a[]="Doris";
$a[]="Eve";
$a[]="Evita";
$a[]="Sunniva";
$a[]="Tove";
$a[]="Unni";
$a[]="Violet";
$a[]="Liza";
$a[]="Elizabeth";
$a[]="Ellen";
$a[]="Wenche";
$a[]="Vicky";

//get the q parameter from URL
$q=$_GET["q"];

//lookup all hints from array if length of q>0
if (strlen($q) > 0)
{
  $hint="";
  for($i=0; $i<count($a); $i++)
  {
    if (strtolower($q)==strtolower(substr($a[$i],0,strlen($q))))
    {
      if ($hint=="")
      {
        $hint=$a[$i];
      }
      else
      {
        $hint=$hint." , ".$a[$i];
      }
    }
  }
}

// Set output to "no suggestion" if no hint were found
// or to the correct values
if ($hint == "")
{
  $response="no suggestion";
}
else
{
  $response=$hint;
}

//output the response
echo $response;
?>

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