I wrote a code to re-read a content of a file (on the server) every time the file is modified. The scenario is like this:
- The webpage is loaded
- If the file (on the server) is newer than the starting time of the page (the time when the webpage was started), the content of the file is read
- If the file is modified later, the content must be read again by PHP script
I tried this using EventSource. Here is the code for the browser:
<html>
<head>
<?php
$startTime = time();
$flag = 0;
?>
<script type="text/javascript" language="javascript">
lastFileTime = <?php echo $startTime; ?>;
var fileTime;
if(typeof(EventSource) !== "undefined") {
var source=new EventSource("getFileTime.php");
source.onmessage = function(event) {
fileTime = parseInt(event.data);
if (fileTime > lastFileTime) {
readFile();
lastFileTime = fileTime;
}
};
}
else {
alert("Sorry, your browser does not support server-sent events.");
}
function readFile() {
<?php
$fid = fopen("file.bin", "rb");
... // Read the content of the file
$flag = $flag + 1;
?>
... // Transfer the content of the file to JavaScript variables
flag = <?php echo $flag; ?>;
}
</script>
</head>
<body>
...
</body>
</html>
And here is the server-side code (getFileTime.php):
<?php
header('Content-Type: text/event-stream');
header('Cache-Control: no-cache');
$filetime = filemtime("file.bin");
echo "data: {$filetime}\n\n";
flush();
?>
When I start the webpage and created file.bin afterwards, readFile() is called for the first time (I checked the value flag = 1. But then, if I modified file.bin again, obviously readFile() is not called. I checked the content of the file; it's still from the previous file, and also flag is still 1. It seems that a PHP script in a JavaScript function can only be called once. How to re-execute the PHP script in a JavaScript function?
