Alonse12

<div class="events__navigation">
    <div class="events__button-inner">
        <button class="events__button events__prev-button" id="prev-button"></button>
    </div>
    <?php $data = [];  ?>
    <?php foreach($posts as $post){ setup_postdata($post); ?>
    <?php $data = get_the_date(); ?>
    <div class="events__date"><?php echo $data; ?></div>
<?php wp_reset_postdata(); } ?>
    <div class="events__button-inner">
        <button class="events__button events__next-button" id="next-button"></button>
    </div>
</div>

function ValidPhone() {
    var re = /^\d[\d\(\)\ -]{4,14}\d$/;
    var myPhone = document.getElementById('phone').value;
    var valid = re.test(myPhone);
    if (valid) output = 'Номер телефона введен правильно!';
    else output = 'Номер телефона введен неправильно!';
    document.getElementById('message').innerHTML = document.getElementById('message').innerHTML+'<br />'+output;
    return valid;
}