var request;var symbol;   //will hold the stock symbolvar numberOfShares;function getStockPrice(sym,shs){    if(sym && shs)  {        symbol=sym;        numberOfShares=shs;        var url="http://www.parkerriver.com/s/stocks?symbol="+sym;        httpRequest("GET",url,true);    }}//event handler for XMLHttpRequestfunction handleResponse(){    if(request.readyState == 4){        if(request.status == 200){            /*Check if the return value is actually a number. If so, multiple by the number            of shares and display the result*/            var stockPrice = request.responseText;            try{                if(isNaN(stockPrice)) { throw new Error("The returned price is an invalid number.");}                if(isNaN(numberOfShares)) { throw new Error("The share amount is an invalid number.");}                var info = "Total stock value: $"+  calcTotal(stockPrice);                displayMsg(document.getElementById("msgDisplay"),info,"black");                document.getElementById("stPrice").style.fontSize="0.9em";                document.getElementById("stPrice").innerHTML ="price: "+stockPrice;            } catch (err) {                displayMsg(document.getElementById("msgDisplay"),"An error occurred: "                        +err.message,"red");            }        } else {            alert("A problem occurred with communicating between the XMLHttpRequest object and the server program.");        }    }//end outer if}/* Initialize a Request object that is already constructed */function initReq(reqType,url,bool){    /* Specify the function that will handle the HTTP response */    request.onreadystatechange=handleResponse;    request.open(reqType,url,bool);    request.send(null);}/* Wrapper function for constructing a Request object. Parameters:  reqType: The HTTP request type such as GET or POST.  url: The URL of the server program.  asynch: Whether to send the request asynchronously or not. */function httpRequest(reqType,url,asynch){    //Mozilla-based browsers    if(window.XMLHttpRequest){        request = new XMLHttpRequest();    } else if (window.ActiveXObject){        request=new ActiveXObject("Msxml2.XMLHTTP");        if (! request){            request=new ActiveXObject("Microsoft.XMLHTTP");        }     }    //the request could still be null if neither ActiveXObject    //initializations succeeded    if(request){       initReq(reqType,url,asynch);    }  else {        alert("Your browser does not permit the use of all "+        "of this application's features!");}}function calcTotal(price){    return stripExtraNumbers(numberOfShares * price);}/*Strip any characters beyond a scale of four characters past the decimal point, as in12.3454 */function stripExtraNumbers(num) {    alert(typeof num)    //check if the number's already okay    //assume a whole number is valid    var numStr =  num.toString();//working with the number as a string    var indx =numStr.indexOf(".");    if(indx == -1)  { return num; }    var chArray = numStr.split(".");    //the second array member includes all the chars after the decimal point    if(chArray[1].length <= 4) { return num; }    //use the Number.toPrecision method to restrict the    //decimal-point numbers to four    //the length of the characters prior to the decimal point plus four    return num.toPrecision(chArray[0].length + 4);}function displayMsg(div,bdyText,txtColor){    //reset DIV content    div.innerHTML="";    div.style.backgroundColor="yellow";    div.style.color=txtColor    div.innerHTML=bdyText;}