Ajax ASP/PHP Example

AJAX ASP/PHP 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: First name: Suggestions:

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Example Explained - The showHint() Function

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

function showHint(str) { var xmlhttp; 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(); }

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:

• Create an XMLHttpRequest object
• Create the function to be executed when the server response is ready
• Send the request off to a file on the server
• Notice that a parameter (q) is added to the URL (with the content of the input field)

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The AJAX Server Page - ASP and PHP

The page on the server called by the JavaScript above is an ASP file called "gethint.asp".
Below we have created two versions of the server file, one written in ASP and one in PHP.

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The 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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The PHP File

Below is the code above rewritten in PHP.
Note: To run the example in PHP, change the value of the url variable (in the HTML file) from "gethint.asp" to "gethint.php".
<?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;
?>