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Editorial Team
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Asked: 2026-06-09T07:32:13+00:00

I am trying to make a simple AJAX program, that always displays the newest

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I am trying to make a simple AJAX program, that always displays the newest text from a file.
It should be retrieving it from the file, wait 2 seconds, and if something changed, write it out.
I tried already but the code doesn’t seem to work. 

<html>
<head>
    <script type="text/javascript">
        function sleep()
        {
            var dt = new Date();
            dt.setTime(dt.getTime() + 2000);
            while (new Date().getTime() < dt.getTime());
        }
        function loadXMLDoc()
        {
        var xmlhttp;
        if (window.XMLHttpRequest)
          {
          xmlhttp=new XMLHttpRequest();
          }
        xmlhttp.onreadystatechange=function()
          {
          if (xmlhttp.readyState==4 && xmlhttp.status==200)
            {
            document.getElementById("myDiv").innerHTML=xmlhttp.responseText;
            }
          }
        xmlhttp.open("GET","ajaxtest.txt",true);
        xmlhttp.send();
        }
    </script>
</head>
<body>
    <script>
    while (0=0)
     {
        loadXMLDoc();

    </script>
        <div id="myDiv"><h2>Status</h2></div>
        <script type="text/javascript">
        setTimeout(loadXMLDoc(),1000)
    }
    </script>

</body>
</html>

How do I get it to check and update the text automatically?

Thanks!

Edit:

Here is the final code for anybody who is interested:

<html>
<head>
    <script type="text/javascript">
        function loadXMLDoc()
        {
        var xmlhttp;
        if (window.XMLHttpRequest)
          {
          xmlhttp=new XMLHttpRequest();
          }
        xmlhttp.onreadystatechange=function()
          {
          if (xmlhttp.readyState==4 && xmlhttp.status==200)
            {
            document.getElementById("myDiv").innerHTML=xmlhttp.responseText;
            }
          }
        xmlhttp.open("GET","status.txt",true);
        xmlhttp.send();
        }
    </script>
</head>
<body>
    <script type="text/javascript">
        loadXMLDoc();
    </script>
    <div id="myDiv">Current Status</div>
    <script type="text/javascript">
        setInterval("loadXMLDoc()", 2000);
    </script>
</body>
</html>
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1 Answer

  1. Editorial Team

    I am not sure if its a typo or a thing from another language. (Like PHP)

    In HTML you cannot have javascript code that goes across multiple script tags.

    Also your while loop has only one = sign, would need two to be comparison.

    But that being said you do want setTimeout or setInterval, because non multi-threaded javascript will just lockup, mulit-threaded ones would wasting processing time as well but not totally lockedup.

    Something like 

    setInterval("loadXMLDoc()", 2000);

    setTimeout executes the first parameter as javascript after the second parameter of milliseconds.

    setInterval executes the like setTimeout except every X milliseconds.

    Both setTimeout and setInterval return a value which can be used to stop the javascript from being executed again.

    That value is used in clearTimeout(value) or clearInterval(value)

    The body of your page would look like this:

    <body>
    <div id="myDiv"><h2>Status</h2></div>
    <script type="text/javascript">
        setInterval("loadXMLDoc()", 2000);
    </script>
</body>
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