bootstrapvalidator/src/js/validator/stringLength.js

(function($) {
    $.fn.bootstrapValidator.validators.stringLength = {
        /**
         * Check if the length of element value is less or more than given number
         *
         * @param {BootstrapValidator} validator The validator plugin instance
         * @param {jQuery} $field Field element
         * @param {Object} options Consists of following keys:
         * - min
         * - max
         * At least one of two keys is required
         * @returns {Boolean}
         */
        validate: function(validator, $field, options) {
            var value = $field.val();
            if (value == '') {
                return true;
            }

            var length = $.trim(value).length;
            if ((options.min && length < options.min) || (options.max && length > options.max)) {
                return false;
            }

            return true;
        }
    };
}(window.jQuery));