how to write a program that displays a message “It’s Fun day” if it's Saturday or Sunday today in javascript

var currentDate = new Date();
currentDate.toString;
var b = currentDate.toString();
var c = b.slice(0,3);
if (c === "Sat"){
    document.write("It's Fun Day")
}else if(c === "Sun"){
    document.write("It's Fun Day")
}else if(c === "Mon"){
    document.write()
}else if(c === "Tue"){
    document.write()
}else if(c === "Wed"){
    document.write()
}else if(c === "Thr"){
    document.write()
}else if(c === "Fri"){
    document.write()
}