Recursive call to a JavaScript method with AJAX call

Greenhorn

Posts: 20

posted 19 years ago

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Following code is successful in refreshing a page every second without flicker (long live AJAX). However, it makes the browser and JBoss server freeze after a while. Any idea/suggestion on the way AJAX call is implemented?

<pre>

on head    
    script tag
 
  var req;
  var which;
 
  function retrieveURL(url) {
  //  alert('retrieveURL' + url + 'Called');
 
    if (window.XMLHttpRequest) { // Non-IE browsers
      req = new XMLHttpRequest();
      req.onreadystatechange = processStateChange;
 
      try {
        req.open("GET", url, true);
      } catch (e) {
        alert(e);
      }
 
      req.send(null);
 
    } else if (window.ActiveXObject) { // IE
 
      req = new ActiveXObject("Microsoft.XMLHTTP");
      if (req) {
        req.onreadystatechange = processStateChange;
        req.open("GET", url, true);
        req.send();
      }
    }
  }
 
 
  function processStateChange() {
 
    if (req.readyState == 4) { // Complete
 
      if (req.status == 200) { // OK response
 
        document.getElementById("theTable").innerHTML = req.responseText;
 
      } else {
// alert("Problem Text: " + req.statusText + "Status: " + req.status );
      }
 
    }
alert("ok "  );
   var timerId = self.setTimeout('retrieveURL(\'http:\/\/localhost\:8080\/PRCSWeb\/panes\/panesDataBrowse.do\')', 1000);
 
  }
 
[closing script tag]
      
         
[on head end]
  
  <body retrieveURL('http://localhost:8080/PRCSWeb/panes/panesDataBrowse.do');" >
    
    <span id="theTable"></span>
        
  body end
 
html end

Eric Pascarello

author

Posts: 15385

posted 19 years ago

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One thing is you are hammering your website with requests. Once a second can cause a heavy load on the box with a lot of people are going to use it. Another thing is eventually the browser eats up memory since it has a bad Garbage Collection.

Eric

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