PHP – Ajax Search

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Ajax is used to communicate with web pages and web servers. Below example demonstrate a search field using with Ajax.

<html>
   <head>     
      <style>
         span{
            color: green;
         }
      </style>      
      <script>
         function showHint(str) {
            if (str.length == 0) {
               document.getElementById("txtHint").innerHTML = "";
               return;
            }
            else {
               var xmlhttp = new XMLHttpRequest();
               xmlhttp.onreadystatechange = function() {
                  if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
                     document.getElementById("txtHint").innerHTML = 
                          xmlhttp.responseText;
                  }
               }
               xmlhttp.open("GET", "php_ajax.php?q=" + str, true);
               xmlhttp.send();
            }
         }
      </script>   
   </head>
   <body>      
      <p><b>Search your favourite tutorials:</b></p>
      <form>
         <input type="text" onkeyup="showHint(this.value)">
      </form>
      <p>Entered Course name: <span id="txtHint"></span></p>
   </body>
</html>

Above code opens a file, name called as php_ajax.php by using with GET method, so we need to create a file, name called as php_ajax.php in the same directory and out put will be attached with txtHint.

php_ajax.php contained array of course names and it returns the value to web browser.

<?php
   // Array with names
   $a[] = "Android";
   $a[] = "B programming language";
   $a[] = "C programming language";
   $a[] = "D programming language";
   $a[] = "euphoria";
   $a[] = "F#";
   $a[] = "GWT";
   $a[] = "HTML5";
   $a[] = "ibatis";
   $a[] = "Java";
   $a[] = "K programming language";
   $a[] = "Lisp";
   $a[] = "Microsoft technologies";
   $a[] = "Networking";
   $a[] = "Open Source";
   $a[] = "PHP";
   $a[] = "Perl";
   $a[] = "QC";
   $a[] = "Restful web services";
   $a[] = "Scrum";
   $a[] = "Testing";
   $a[] = "UML";
   $a[] = "VB Script";
   $a[] = "Web Technologies";
   $a[] = "Xerox Technology";
   $a[] = "YQL";
   $a[] = "ZOPL";
 
   $q = $_REQUEST["q"];
   $hint = "";
 
   if ($q !== "") {
      $q = strtolower($q);
      $len=strlen($q);
      foreach($a as $name) {
         if (stristr($q, substr($name, 0, $len))) {
            if ($hint === "") 
               $hint = $name;
            else 
               $hint .= ", $name";
         }
      }
   }
   echo $hint === "" ? "Please enter a valid course name" : $hint;
?>

你可以在输入框中依次输入 a, b, p 看看有何不同