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Old 06-28-2010, 02:59 PM   #1
newbie_0404
LQ Newbie
 
Registered: May 2010
Posts: 13

Rep: Reputation: 0
Why wouldnt this javascript run ?


Hello Everyone,
I am new to writing javascripts. I am working on a web-interface that has to show certain data in real-time (update it every 2 seconds). I figured including an iframe and reloading it with javascript would be the best bet. So to see if it works I wrote this test code. But it doesnt reload the iframe every 2 seconds. Can anyone point out where I am going wrong ?


this is the code for hello.html
PHP Code:
<html>
<
body>
<
script type="text/javascript">
function 
reloadIt()
{
frm=document.getElementsByName("iframe1")[0];//we get the iframe object
frm.src=frm.src;//or you can set the src to a new src.
setTimeout("reloadIt()",2000);//the function will run every 2 seconds
}
</script>
<h1>This is a test</h1>
<p>The random number generated is 
<iframe id="iframe1" name="iframe1" height="30" width="300"
src="hello.php"></iframe>
</p>
</body>
</html> 
and this is the code for hello.php

PHP Code:
<?php
$i
=rand(0,10);
print (
"$i");
?>
Any help with this would be highly appreciated.

Thanks
 
Old 06-29-2010, 03:53 AM   #2
timmeke
Senior Member
 
Registered: Nov 2005
Location: Belgium
Distribution: Red Hat, Fedora
Posts: 1,515

Rep: Reputation: 61
Did you try to change the src-URL for the iframe to a complete URL?
Remember that iframe/javascript are on client's side, php on server's.
 
Old 06-29-2010, 08:35 AM   #3
zirias
Member
 
Registered: Jun 2010
Posts: 361

Rep: Reputation: 59
Just an idea for you how to solve this kind of problem cleaner.

Service-Side (REST-style JSON service):

getRandomNumber.php:
PHP Code:
<?php
header
("Content-Type: text/x-json");
$i rand(0,10);
print(
'{ "value" : "'.$i.'" }');
?>
Client-Side (XmlHttpRequest):

PeriodicUpdater.js:
Code:
(function() {

  function createXmlHttpRequestObject()
  {
    var xmlhttp = false;
    try
    {
      xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch (e)
    {
      try
      {
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
      }
      catch (e)
      {
        xmlhttp = false;
      }
    }
    if (!xmlhttp && typeof XMLHttpRequest != 'undefined')
    {
      try
      {
        xmlhttp = new XMLHttpRequest();
      }
      catch (e)
      {
        xmlhttp = false;
      }
    }
    if (!xmlhttp && window.createRequest)
    {
      try
      {
        xmlhttp = window.createRequest();
      }
      catch (e)
      {
        xmlhttp = false;
      }
    }
    return xmlhttp;
  }

  window.PeriodicUpdater = function(element, service, period);
  {
    if (typeof(element) == "string")
    {
      this._element = window.document.getElementById(element);
    }
    else
    {
      this._element = element;
    }
    this._service = service;
    this._period = period;
    this._request = createXmlHttpRequestObject();
    this._active = false;
  };

  PeriodicUpdater.prototype = {

    start: function()
    {
      if (!this._request) { return; }
      if (this._active) { return; }
      this._active = true;
      window.setTimeout(this._update(), this._period);
    },

    stop: function()
    {
      this._active = false;
    },

    _update: function()
    {
      if (!this._active) { return; }
      this._request.open("GET", this._service, true);
      this._request.onReadyStateChange = function() {
        if (this._request.readyState != 4) { return; }
        var response = eval('(' + this._request.responseText + ')');
        while (this._element.hasChildNodes())
        {
          this._element.removeChild(this._element.firstChild);
        }
        this._element.appendChild(window.document.createTextNode(response.value));
      };
      window.setTimeout(this._update(), this._period);
    }
  };
})();
Usage in html:
Code:
<div id="update"></div>
<script type="text/javascript">
var updater = new PeriodicUpdater("update", "http://example.com/getRandomNumber.php", 2000);
updater.start();
</script>
This code is untested (but the whole XmlHttpRequest boilerplate is copy&paste from a working script, so there should be no major problems with it)
 
  


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