PHP Example - AJAX实时搜索
AJAX can be used to create more user-friendly and interactive searches.
AJAX实时搜索
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:
- 创建 XMLHttpRequest 对象
- 创建在服务器响应准备就绪时执行的函数
- 将请求发送到服务器上的文件
- Notice that a parameter (q) is added to the URL (with the content of the input field)
PHP 文件
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"
