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PHP Example - AJAX Live Search


AJAX can be used to create more user-friendly and interactive searches.


AJAX Live Search

The following example will demonstrate a live search, where you get search results while you type.

Live search has many benefits compared to traditional searching:

  • Results are shown as you type
  • Results narrow as you continue typing
  • If results become too narrow, remove characters to see a broader result

Search for a W3Schools page in the input field below:

The results in the example above are found in an XML file (links.xml). To make this example small and simple, only six results are available.


Example Explained - The HTML Page

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

<html>
<head>
<script>
function showResult(str)
{
if (str.length==0)
  {
  document.getElementById("livesearch").innerHTML="";
  document.getElementById("livesearch").style.border="0px";
  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("livesearch").innerHTML=xmlhttp.responseText;
    document.getElementById("livesearch").style.border="1px solid #A5ACB2";
    }
  }
xmlhttp.open("GET","livesearch.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>

<form>
<input type="text" size="30" onkeyup="showResult(this.value)">
<div id="livesearch"></div>
</form>

</body>
</html>

Source code explanation:

If the input field is empty (str.length==0), the function clears the content of the livesearch placeholder and exits the function.

If the input field is not empty, the showResult() 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)

The PHP File

The page on the server called by the JavaScript above is a PHP file called "livesearch.php".

The source code in "livesearch.php" searches an XML file for titles matching the search string and returns the result:

<?php
$xmlDoc=new DOMDocument();
$xmlDoc->load("links.xml");

$x=$xmlDoc->getElementsByTagName('link');

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

//lookup all links from the xml file if length of q>0
if (strlen($q)>0)
{
$hint="";
for($i=0; $i<($x->length); $i++)
  {
  $y=$x->item($i)->getElementsByTagName('title');
  $z=$x->item($i)->getElementsByTagName('url');
  if ($y->item(0)->nodeType==1)
    {
    //find a link matching the search text
    if (stristr($y->item(0)->childNodes->item(0)->nodeValue,$q))
      {
      if ($hint=="")
        {
        $hint="<a href='" .
        $z->item(0)->childNodes->item(0)->nodeValue .
        "' target='_blank'>" .
        $y->item(0)->childNodes->item(0)->nodeValue . "</a>";
        }
      else
        {
        $hint=$hint . "<br /><a href='" .
        $z->item(0)->childNodes->item(0)->nodeValue .
        "' target='_blank'>" .
        $y->item(0)->childNodes->item(0)->nodeValue . "</a>";
        }
      }
    }
  }
}

// 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;
?>

If there is any text sent from the JavaScript (strlen($q) > 0), the following happens:

  • Load an XML file into a new XML DOM object
  • Loop through all <title> elements to find matches from the text sent from the JavaScript
  • Sets the correct url and title in the "$response" variable. If more than one match is found, all matches are added to the variable
  • If no matches are found, the $response variable is set to "no suggestion"


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