output in javascript

                                    console.log("Who's Joe?")

                                    console.log(a);             // write to the browser console
document.write(a);          // write to the HTML
alert(a);                   // output in an alert box
confirm("Really?");         // yes/no dialog, returns true/false depending on user click
prompt("Your age?","0");    // input dialog. Second argument is the initial value

                                    console.log("Hello World!");
alert("Console has been updated.");