PHP
Example - AJAX Poll
AJAX Poll
The
following example will demonstrate a poll where the result is shown without
reloading.
Do you like
PHP and AJAX so far?
Yes:
No:
Example
Explained - The HTML Page
When a user
chooses an option above, a function called "getVote()" is executed.
The function is triggered by the "onclick" event:
<html>
<head>
<script>
function
getVote(int) {
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 (this.readyState==4 &&
this.status==200) {
document.getElementById("poll").innerHTML=this.responseText;
}
}
xmlhttp.open("GET","poll_vote.php?vote="+int,true);
xmlhttp.send();
}
</script>
</head>
<body>
<div
id="poll">
<h3>Do
you like PHP and AJAX so far?</h3>
<form>
Yes:
<input
type="radio" name="vote" value="0"
onclick="getVote(this.value)">
<br>No:
<input
type="radio" name="vote" value="1"
onclick="getVote(this.value)">
</form>
</div>
</body>
</html>
The
getVote() function does 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 (vote) is added to the URL (with the value of the yes or no option)
The PHP File
The page on
the server called by the JavaScript above is a PHP file called
"poll_vote.php":
<?php
$vote
= $_REQUEST['vote'];
//get
content of textfile
$filename
= "poll_result.txt";
$content
= file($filename);
//put
content in array
$array
= explode("||", $content[0]);
$yes
= $array[0];
$no
= $array[1];
if
($vote == 0) {
$yes = $yes + 1;
}
if
($vote == 1) {
$no = $no + 1;
}
//insert
votes to txt file
$insertvote
= $yes."||".$no;
$fp
= fopen($filename,"w");
fputs($fp,$insertvote);
fclose($fp);
?>
<h2>Result:</h2>
<table>
<tr>
<td>Yes:</td>
<td>
<img
src="poll.gif"
width='<?php
echo(100*round($yes/($no+$yes),2)); ?>'
height='20'>
<?php
echo(100*round($yes/($no+$yes),2)); ?>%
</td>
</tr>
<tr>
<td>No:</td>
<td>
<img
src="poll.gif"
width='<?php
echo(100*round($no/($no+$yes),2)); ?>'
height='20'>
<?php
echo(100*round($no/($no+$yes),2)); ?>%
</td>
</tr>
</table>
The value is
sent from the JavaScript, and the following happens:
Get the
content of the "poll_result.txt" file
Put the
content of the file in variables and add one to the selected variable
Write the
result to the "poll_result.txt" file
Output a
graphical representation of the poll result
The Text
File
The text
file (poll_result.txt) is where we store the data from the poll.
It is stored
like this:
0||0
The first
number represents the "Yes" votes, the second number represents the
"No" votes.
Note: Remember
to allow your web server to edit the text file. Do NOT give everyone access,
just the web server (PHP).
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