Phone mask for Brazilian phone numbers

brazilian-phone-mask.js

/* REQUIRES jQUERY */

    // Mask for the area code
var patternDDD = /^(\d\d)(.+)/,
    // Mask for the de facto number
    patternPhone = /^(\d\d)(\d)?(\d{4})(\d{4})$/;
    // Sometimes the phone number (especially mobile phones) may have an
    // additional digit; hence the optional \d in the second group.

// Change the id below to your id, or class, or whatever.
// works better (i.e., only tested) with an input[type=text]
// by the way, this is the only part that requires jQuery...
// maybe you don't really need jQuery.
$('#id_of_your_phone_number_text_input').on('input change', function () {
    var value = this.value,
        stripped = value.replace(/\D/g, '').slice(0, 11), // get numeric characters only
        string,
        match;

    // Matching the entire phone number
    if (patternPhone.test(stripped)) {
        match = stripped.match(patternPhone).slice(1);
        // if the additional digit is present, place one additional %s
        string = match[1] ? '(%s) %s %s-%s' : '(%s) %s-%s';

        // I miss a good 'format' function for JS.
        match.forEach(function (m) {
            if (m) string = string.replace('%s', m);
        });

        this.value = string.trim();
    }

    // matching only the area code
    else if (patternDDD.test(stripped)) {
        match = stripped.match(patternDDD);
        string = '(' + match[1] + ') ' + match[2];

        this.value = string.trim();
    }
});