Use 'event.currentTarget.performance.navigation.type' to determine the type of navigation. This is working in IE, FF and Chrome.
function CallbackFunction(event) {
if(window.event) {
if (window.event.clientX < 40 && window.event.clientY < 0) {
alert("back button is clicked");
}else{
alert("refresh button is clicked");
}
}else{
if (event.currentTarget.performance.navigation.type == 2) {
alert("back button is clicked");
}
if (event.currentTarget.performance.navigation.type == 1) {
alert("refresh button is clicked");
}
}
}