var browser=navigator.appName;
                var b_version=navigator.appVersion;



<a href="http://www.justetc.net" target="_blank">
<img border="0" alt="hello" src="b_pink.gif" id="b1" width="26" height="26" onmouseover="mouseOver()" onmouseout="mouseOut()" />



Place the following code under script tag/in a javascript file

function mouseOver()
{
   document.getElementById("b1").src ="b_blue.gif";
}

function mouseOut()
{
   document.getElementById("b1").src ="b_pink.gif";
}






<map name="planetmap">

<area shape ="rect" coords ="0,0,82,126"
onMouseOver="writeText('You are over the target area')"
href ="target.htm" target ="_blank" alt="target" />

var t1=setTimeout("document.getElementById('id1').value='2 seconds!'",2000);
var t2=setTimeout("document.getElementById('id1').value='4 seconds!'",4000);
var t3=setTimeout("document.getElementById('id1').value='6 seconds!'",6000);

Direct Instance: 

pObj=new Object();
pObj.firstname="John";
pObj.lastname="Doe";
pObj.age=50;
pObj.eyecolor="blue";

document.write(pObj.firstname + " is " + pObj.age + " years 

function car(brand,make,model)
{
this.brand=brand;
this.make=make;
this.model=model;
}
var myCar=new car("Honda","2009","Accord");
document.write(myCar.brand +  myCar.make + myCar.model );

try
{
}
catch(err)
{
}


Under script tag/javascript file:

onerror=handleErr;
var alertTxt = "" 

function handleErr(msg, url, l)
{
   alertTxt = "Error Information:.\n\n";
   alertTxt += msg + "\n";
   alertTxt += url + "\n";
   alertTxt += l + "\n\n";
   alertTxt += "Click OK to continue.\n\n";
   alert(alertTxt);
   return true;
}


var x;
var myFriends= new Array();
myFriends[0] = "Shafiq";
myFriends[1] = "Rafiq";
myFriends[2] = "Abba";
myFriends[3] = "Amma";

for (x in myFriends)
{
   document.write(myFriends[x] + "
");
}


var d = new Date();
theDay=d.getDay();
switch (theDay)
{
case 5:
  document.write("Friday");
  break;
case 6:
  document.write("Saturday");
  break;
case 0:
  document.write("Sunday");
  break;
}

   var pattern = new RegExp("e","g");
   do
   {
     result=pattern .exec("This is the line where the regular expression will be searched on");
     document.write(result);
   }
   while (result!=null)

    function validateCollectPaymentInformationForm()
    {
        var method, name, number, expiry, errMsg
        
        errMsg = "";
        
        method = document.getElementById('paymentMethod');
        name =   document.getElementById('txtCCName');
        number = document.getElementById('txtCCNumber');
        
        if (method.value == "" || method.value == "0" || method.value == null){
            
            errMsg = "Please select a payment method \n";
            
            
        }
        
        if (name.value == "" || name.value == null){
            
            errMsg = errMsg + 'Please write down your name  \n';
            
            
        }
        
        if (number.value == "" || number.value == null){
            
            errMsg = errMsg + 'Please provide credit card number  \n';
                
        }else if (number.value.length < 16 ){
            errMsg = errMsg + 'Invalid credit card number  \n';
        }
        
        
        
        if (errMsg.length > 0 ){
            alert(errMsg);
            method.focus();
            return false;            
        }else{        
            return true;
        }        
        return false;    
    }


    function validateCollectPaymentInformationForm()
    {
        var method, name, number, expiry, errMsg
        
        
        
        method = document.getElementById('paymentMethod');
        name =   document.getElementById('txtCCName');
        number = document.getElementById('txtCCNumber');
        
        if (method.value == "" || method.value == "0" || method.value == null){
            alert('Please select a payment method');
            method.focus();
            return false;
            
        }
        
        if (name.value == "" || name.value == null){
            alert('Please write down your name');            
            name.focus();
            return false;
            
        }
        
        if (number.value == "" || number.value == null){
            alert('Please provide credit card number');            
            number.focus();
            return false;            
        }else if (number.value.length < 16 ){
            alert('Invalid card number');            
            number.focus();
            return false;    
        }
        
        
            
        return true;
    }