Help me understand such AJAX code snippet

Below are my AJAX code snippet.
In rescanNetwork(), there are two calls of newAJAXCommand(). The first one “newAJAXCommand(‘scan.cgi?scan=1’);” The second one is “setTimeout(“newAJAXCommand(‘status.xml’, updateStatus, false)”, 50)”
The content of scan.cgi is kind of “Success! _~scan~“. My questions are:

“`
// Initiates a new AJAX command
// url: the url to access
// container: the document ID to fill, or a function to call with response XML (optional)
// repeat: true to repeat this call indefinitely (optional)
// data: an URL encoded string to be submitted as POST data (optional)
function newAJAXCommand(url, container, repeat, data)
{
// Set up our object
var newAjax = new Object();
var theTimer = new Date();
newAjax.url = url;
newAjax.container = container;
newAjax.repeat = repeat;
newAjax.ajaxReq = null;

// Create and send the request
if (window.XMLHttpRequest) {
newAjax.ajaxReq = new XMLHttpRequest();
newAjax.ajaxReq.open((data==null)?”GET”:”POST”, newAjax.url, true);
newAjax.ajaxReq.send(data);
// If we’re using IE6 style (maybe 5.5 compatible too)
} else if (window.ActiveXObject) {
newAjax.ajaxReq = new ActiveXObject(“Microsoft.XMLHTTP”);
if (newAjax.ajaxReq) {
newAjax.ajaxReq.open((data==null)?”GET”:”POST”, newAjax.url, true);
newAjax.ajaxReq.send(data);
}
}

newAjax.lastCalled = theTimer.getTime();

// Store in our array
ajaxList.push(newAjax);
}

…….
function updateStatus(xmlData)
{
……
}
…..

function rescanNetwork()
{
scanDots = 0;
printButtonName();
document.getElementById(“rescan”).disabled = true;

// Generate a request to hardware to issue a rescan
newAJAXCommand(‘scan.cgi?scan=1’);

// Delete old table, replace with new table after scan is finished
deleteScanTable();

currBss = 0; // Reset the current bss pointer

setTimeout(“newAJAXCommand(‘status.xml’, updateStatus, false)”, 50);
}
“`

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