PHP Examples -AJAX Live Search

AJAX can provide users with a more friendly and interactive search experience.

AJAX Live Search

In the following example, we will demonstrate a live search. You can get search results as you type.

Live search has many advantages compared with traditional search:

  • When typing data, matching results are displayed
  • When you continue typing data, the results are filtered
  • If there are too few results, delete characters to get a wider range

Enter "HTML" in the text box below to search for pages containing HTML:

The results in the above example are looked up in an XML file (links.xml). To keep this example small and simple, we only provide 6 results.

Example explanation - HTML page

When the user types characters in the input box above, the "showResult()" function is executed. This 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)
    {// IE7+, Firefox, Chrome, Opera, Safari 浏览器执行
        xmlhttp=new XMLHttpRequest();
    }
    else
    {// IE6, IE5 浏览器执行
        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 box is empty (str.length==0), the function clears the content of the livesearch placeholder and exits the function.

If the input box is not empty, showResult() performs the following steps:

  • Create an XMLHttpRequest object
  • Create a function to execute when the server response is ready
  • Send a request to the file on the server
  • Note the parameter (q) added to the end of the URL (containing the content of the input box)

PHP File

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

The source code in "livesearch.php" searches the XML file for titles that match the search string and returns the results:

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

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

// 从 URL 中获取参数 q 的值
$q=$_GET["q"];

// 如果 q 参数存在则从 xml 文件中查找数据
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)
        {
            // 找到匹配搜索的链接
            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>";
                }
            }
        }
    }
}

// 如果没找到则返回 "no suggestion"
if ($hint=="")
{
    $response="no suggestion";
}
else
{
    $response=$hint;
}

// 输出结果
echo $response;
?>

If JavaScript sends any text (i.e., strlen($q) > 0), the following happens:

  • Load the XML file into a new XML DOM object
  • Loop through all <title> elements to find matches for the text sent by JavaScript
  • Set 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 match is found, set the $response variable to "no suggestion".
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