HTML and CSS Reference
In-Depth Information
When an alert dialog box is being displayed, the execution of the program code halts
until the user clicks the OK button. The alert message is limited to plain text and cannot
include HTML-formatted text. For more elaborate alert dialog boxes, you'd have to use
JavaScript to construct the appearance and content of a custom dialog box yourself; that
topic is beyond the scope of this tutorial.
Alert dialog boxes require no input from users other than to click the OK button to
continue the execution of the program code. The confirm() method
You can add a line return
to the dialog box message
text by including the
character code \n within
the text string.
confirm( message )
displays a confirm dialog box that prompts users for a yes or no response, where
message is the text of the message that users must confirm or reject. For example, the
confirm(“Load a new puzzle?”)
would display the dialog box shown in Figure 13-30.
Figure 13-30
browser window confirm dialog box
A confirm dialog box returns the result of a user's action as a Boolean value. If the user
clicks the OK button, a value of true is returned; otherwise, a value of false is returned.
For example, the user determines the Boolean value of the showProfile variable in the fol-
lowing command based on the button he or she clicks in the confirm dialog box:
var showProfile = confirm(“Show user profile?”);
If you need a text string returned instead of a Boolean value, you can display a prompt
dialog box by using the method
prompt( message , default )
where message is the text of the prompt message, and default is the default text string
returned by the dialog box if the OK button is clicked. The statement
var userName = prompt(“User Name”, “Enter your name”)
would display the dialog box shown in Figure 13-31, with the text entered by the user
saved to the userName variable. If the user clicked the Cancel button, no value would be
stored in the userName variable.
Figure 13-31
browser window prompt dialog box
Note that both the confirm() and prompt() methods also halt the actions of the
program until the user clicks either the OK or Cancel button.
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