Customized Java scripts Alerts

Here is the code through which we can override the JavaScript window.Alert() and write our own custom alerts where we can define our own title, text in the button of alert box :
Just we need to follow the below files and enjoy the customzied Javascript Alerts.

CSS Code :
just copy the below code in the "style type="text/css" " tag and "/style"

#alertBox {
position:relative;
width:300px;
min-height:100px;
margin-top:50px;
border:2px solid #000;
background-color:#F2F5F6;
background-image:url(alert.png);
background-repeat:no-repeat;
background-position:20px 30px;
}
#alertBox h1 {
margin:0;
font:bold 0.9em verdana,arial;
background-color:#78919B;
color:#FFF;
border-bottom:1px solid #000;
padding:2px 0 2px 5px;
}
#alertBox p {
font:0.7em verdana,arial;
height:50px;
padding-left:5px;
margin-left:55px;
}
#alertBox #closeBtn {
display:block;
position:relative;
margin:5px auto;
padding:3px;
border:2px solid #000;
width:70px;
font:0.7em verdana,arial;
text-transform:uppercase;
text-align:center;
color:#FFF;
background-color:#78919B;
text-decoration:none;
}

JavaScript Code :

just copy the below code in the javaScript code "
script type="text/javascript"" " tag and "/script"

var ALERT_TITLE = "Oops!";
var ALERT_BUTTON_TEXT = "Ok";
if(document.getElementById) {
window.alert = function(txt) {
createCustomAlert(txt);
}
}
function createCustomAlert(txt) {
d = document;
if(d.getElementById("modalContainer")) return;
mObj = d.getElementsByTagName("body")[0].appendChild(d.createElement("div"));
mObj.id = "modalContainer";
mObj.style.height = d.documentElement.scrollHeight + "px";
alertObj = mObj.appendChild(d.createElement("div"));
alertObj.id = "alertBox";
if(d.all && !window.opera) alertObj.style.top = document.documentElement.scrollTop + "px";
alertObj.style.left = (d.documentElement.scrollWidth - alertObj.offsetWidth)/2 + "px";
alertObj.style.visiblity="visible";
h1 = alertObj.appendChild(d.createElement("h1"));
h1.appendChild(d.createTextNode(ALERT_TITLE));
msg = alertObj.appendChild(d.createElement("p"));
//msg.appendChild(d.createTextNode(txt));
msg.innerHTML = txt;
btn = alertObj.appendChild(d.createElement("a"));
btn.id = "closeBtn";
btn.appendChild(d.createTextNode(ALERT_BUTTON_TEXT));
btn.href = "#";
btn.focus();
btn.onclick = function() { removeCustomAlert();return false; }
alertObj.style.display = "block";
}
function removeCustomAlert() {
document.getElementsByTagName("body")[0].removeChild(document.getElementById("modalContainer"));
}

HTML Code :
<input type="button" value = "Test the alert" onclick="alert('This is a custom alert dialog that was created by over-riding the window.alert method.');" />