JavaScript 2.0-The Complete Reference, Second ... - freecodingtutorial

Note The typical rendering of the alert includes an icon indicating a warning, regardless of the
meaning of the message being presented.
The basic syntax for alert() is
window.alert(string);
or for shorthand,
alert(string);
as the Window object can be assumed.
The string passed to any dialog like an alert may be either a variable or the result of an
expression. If you pass another form of data, it should be coerced into a string. All of the
following examples are valid uses of the alert() method:
alert("Hi there from JavaScript! ");
alert("Hi "+username+" from Javascript");
var messageString = "Hi again!";
alert(messageString);
An alert window is page modal, meaning that it must receive focus and be cleared before the
user is allowed to continue activity with the page.
Note A good use of alert dialogs is for debugging messages. If you are ever in doubt of where a
script is executing or what current variables are set at and you don’t want to use a
debugger, you can use an alert to display useful debugging information.
Confirm
The confirm() method for the window object creates a window that displays a message for a
user to respond to by clicking either an OK button to agree with the message or a Cancel
button to disagree with the message. A typical rendering is shown here.
The writing of the confirmation question may influence the usability of the dialog significantly.
Many confirmation messages are best answered with a Yes or No button rather than OK or
Cancel, as shown by the dialog at right.
Unfortunately, using the basic JavaScript confirmation method, there is no possibility to change
the button strings. However, it is possible to write your own form of confirmation.
The basic syntax of the confirm() method is