Function maskMobile

Masks an international mobile phone number, regardless of its country.

The local number keeps its leading digits in plain text, replaces the middle 4 digits with *, and keeps the trailing 4 digits in plain text. The country calling code is dropped from the result, so the masked value is a pure local number.

The text may be:

• a plain local number, e.g. 13800138000;
• an E.164 number with a + prefix, e.g. +8613800138000;
• an E.164 number followed by a dash, e.g. +86-13812345678.

The optional alphaOrDial hints the country of the number:

• a two-letter ISO country code (case-insensitive, e.g. CN, US); or
• a dial code (e.g. +86, 86). When it is a dial code and text has no + prefix, it is prepended to text so that libphonenumber-js can detect the country automatically.

When alphaOrDial is omitted, text is parsed directly and the country is auto-detected, which requires text to carry a + country code; otherwise the number cannot be resolved and undefined is returned.

A number is masked only when libphonenumber-js can resolve it to a country and extract its local number; input that cannot be parsed (e.g. a bare local number without a country hint, or an overly short number) yields undefined.