mask([mask], [placeholder])

Sets or gets a text mask formatter with a specified mask string and a placeholder character.

A mask string defines the allowed characters at each position.
Each special character in the mask has a meaning:

# — A digit (0–9).
U — An uppercase letter (A–Z).
L — A lowercase letter (a–z).
A — Any letter (A–Z or a–z).
? — Any letter (case-insensitive).
* — Any character (letter or digit).
H — A hexadecimal character (0–9, A–F, a–f).
. , , , : , - , / — These are treated as literal characters and appear in the formatted text.
' (single quote) — Escape character. Place before a literal mask character if you don’t want it treated specially.
Example: "'#'###" means literal # followed by three digits.

Example masks:

Name	Type	Default	Description
`[mask]`	string		Text mask string. Set to empty string or `null` to clear the mask.
`[placeholder]`	string	"_"	A character to use for empty characters in the mask. Default is "_" character.

When setting a mask, returns this TextField component for chaining. When called without arguments, returns the current mask information object.

Type: Object | TextField

Examples:

// U.S. Phone number mask
textfield.mask("(###) ###-####", "_");

// Date input (MM/DD/YYYY)
textfield.mask("##/##/####", "_");

// Time input (HH:MM)
textfield.mask("##:##", "_");

// Product code input
textfield.mask("AAAA-####", "_");

// Get current mask settings
const info = textfield.mask();
console.log(info.mask, info.placeholder);