[Solved] document.write is killing page

as everybody suggested. document.write will clear everything from the DOM.
the best way to write this would be to have a DIV in your HTML and set that div in your javascript code.

here’s what your HTML should look like

<div id="page_message" style="display: none;"></div>
<div class="countdown_out">
<div id="countdown_title">NFL Season Opener Countdown</div>
<div class="countdown_position">
    <div class="countdownBox">
        <div class="countdown_time_category">Days</div>
        <div id="daysBox" class="countdown_time"></div>
    <div class="countdownBox">
        <div class="countdown_time_category">Hours</div>
        <div id="hoursBox" class="countdown_time"></div>
    <div class="countdownBox">
        <div class="countdown_time_category">Minutes</div>
        <div id="minsBox" class="countdown_time"></div>
    <div class="countdownBox">
        <div class="countdown_time_category">Seconds</div>
        <div id="secsBox" class="countdown_time"></div>

and update your Javascript code to look like this.

<script type="text/javascript">
    function cdtd() {
        var nflSeason = new Date("September 10, 2015 08:30:00");
        var now = new Date();
        var timeDiff = nflSeason.getTime() - now.getTime();
        if (timeDiff < 0) {
            document.getElementById("page_message").innerHTML = 'The NFL Season is here!!';
            document.getElementById("page_message").style.display = 'inline';

            //Run any code needed for countdown completion here.

        var seconds = Math.floor(timeDiff / 1000);
        var minutes = Math.floor(seconds / 60);
        var hours = Math.floor(minutes / 60);
        var days = Math.floor(hours / 24);
        hours %= 24;
        minutes %= 60;
        seconds %= 60;

        document.getElementById("daysBox").innerHTML = days;
        document.getElementById("hoursBox").innerHTML = hours;
        document.getElementById("minsBox").innerHTML = minutes;
        document.getElementById("secsBox").innerHTML = seconds;

        var timer = setTimeout('cdtd()', 1000);

Hope this helps.

solved document.write is killing page