Restricting text input

Since input text fields are often used for forms or dialog boxes in applications, you may want to limit the types of characters a user can enter in a text field, or even keep the text hidden —for example, for a password. The flash.text.TextField class has a displayAsPassword property and a restrict property that you can set to control user input.

The displayAsPassword property simply hides the text (displaying it as a series of asterisks) as the user types it. When displayAsPassword is set to true, the Cut and Copy commands and their corresponding keyboard shortcuts do not function. As the following example shows, you assign the displayAsPassword property just as you would other properties, such as background and color:

myTextBox.type = TextFieldType.INPUT;
myTextBox.background = true;
myTextBox.displayAsPassword = true;
addChild(myTextBox);

The restrict property is a little more complicated since you must specify which characters the user is allowed to type in an input text field. You can allow specific letters, numbers, or ranges of letters, numbers, and characters. The following code allows the user to enter only uppercase letters (and not numbers or special characters) in the text field:

myTextBox.restrict = "A-Z";

ActionScript 3.0 uses hyphens to define ranges, and carets to define excluded characters. For more information about defining what is restricted in an input text field, see the flash.text.TextField.restrict property entry in the ActionScript 3.0 Reference.

Note: If you use the flash.text.TextField.restrict property, the runtime automatically converts restricted letters to the allowed case. If you use the fl.text.TLFTextField.restrict property (that is, if you use a TLF text field), the runtime ignores restricted letters.