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POis it possible to assign a value only once for php variable in continuous ajax request?
 

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  1. POis it possible to assign a value only once for php variable in continuous ajax request?
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    <p>Well I have some simple text file, I am trying to read that file contents using php and update it to the user.I was setting up the ajax request for every 2 seconds but the problem is the file wont be updated for every 2 seconds may be 15 or 30 or 1 minute long.So i thought of doing this</p> <p>check the last modified time of file and if it is different then only update it to the user but here where I am stucked at.</p> <pre><code> Javascript functions function read() { read_text(); t=setTimeout("read()",200); } function read_text() { var xmlhttp; 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 (xmlhttp.readyState==4 &amp;&amp; xmlhttp.status==200) { document.getElementById('read').innerHTML = xmlhttp.responseText; } } xmlhttp.open("GET","demo.php",true); xmlhttp.send(); } </code></pre> <p><strong>My php file</strong></p> <pre><code>&lt;?php $a = fileattime("filenam"); $b = fileattime("filenam"); if($b &gt; $a ) { echo "update contents"; $a = $ b; } ?&gt; </code></pre> <p>I thought to store the last modified time of file in <code>$a</code> variable and compare the value with <code>$b</code> variable but here <code>$a</code> will be overwritten with the new value for every ajax request. I want <code>$a</code> to be assigned a value only once, I mean for the first ajax request then later on compare it with <code>$b</code> value and if <code>$b</code> is greater than <code>$a</code> then update the contents to user then fill up <code>$a</code> with <code>$b</code></p> <p>but this is where i stucked at. Any help is greatly appreciated.Thanks</p>
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