Limit any text field by adding to data attributes to the field.

LimitText.js

(function (exports, $) {
    "use strict";
    var defaults = {
            regexAttr: 'data-regex',
            maxAttr: 'data-max'
        },
        allowedKeys = "Backspace Enter Tab Left Right Down Up",
        runRegex = function () {
            var value = this.$el.val(),
                array = value.match(this.regex),
                limited = (array) ? array[0] : "";
            if (value === limited) return;
            this.$el.val(limited);
        },
        validateMax = function () {
            return (this.$el.val().length >= this.max) ? false : true;
        },
        bindEvents = function () {
            var self = this;
            if (this.regex) {
                this.$el.on('keyup blur', function () {
                    runRegex.call(self);
                });
            }
            if (this.max > 0) {
                this.$el.on('keypress', function (e) {
                    if (this.selectionStart != this.selectionEnd) return;
                    if (allowedKeys.indexOf(e.key) > -1) return;
                    return validateMax.call(self) ? true : e.preventDefault();
                });
            }
        },
        init = function (el, options) {
            var regexString;
            this.$el = $(el);
            if (!this.$el.length) return false;
            this.opts = $.extend({}, defaults, options);
            regexString = this.$el.attr(this.opts.regexAttr);
            if (regexString) {
                this.regex = new RegExp(regexString, 'g');
            }
            this.max = parseInt(this.$el.attr(this.opts.maxAttr), 10);
            bindEvents.call(this);
            return true;
        };
    exports.Limit = function (el, options) {
        this.result = init.call(this, el, options);
    };
}(main, jQuery));