// This line causes the message to display on loading the html topic
alert ("Welcome to the world of javascript.");

// This function will cause the message to display only when called in some way
// for example, a button click
function call_alert()
{
alert ("Welcome to the world of javascript.");
}

// This function displays a popup window when called.
function popup1()
{
var popwindow=
window.open("popup_demo.htm","","top=200,left=300,width=275,height=200");
}