/* HTML maxlength counts UTF-16 units; the server counts Unicode code points. */
(function () {
    'use strict';
    function initialize() {
        document.querySelectorAll('[data-character-limit]').forEach(function (field) {
            const limit = Number(field.dataset.characterLimit);
            function validate() {
                const tooLong = Array.from(field.value.replace(/^[ \t\n\r\0\v]+|[ \t\n\r\0\v]+$/g, '')).length > limit;
                field.setCustomValidity(tooLong ? 'Please enter ' + limit + ' characters or fewer.' : '');
            }
            field.addEventListener('input', validate);
            validate();
        });
    }
    if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', initialize);
    else initialize();
}());