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php ajax livesearch

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;

  }

  var xmlhttp=new XMLHttpRequest();

 

xmlhttp.onreadystatechange=function() {

 

  if (this.readyState==4 && this.status==200) {

 

 

  document.getElementById("livesearch").innerHTML=this.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 was 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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