JavaScript倒数计时器Safari失败

Question

我的倒数计时器在Chrome中工作正常，但在Safari中失败。 有什么想法吗？一些阅读表明新的日期存在问题，但是尝试更改此日期失败了。

const launchDate = new Date("Jul 12, 2018 09:00:00 GMT-0400").getTime();
let timer = setInterval(function() {
    const today = new Date().getTime();
    const diff = launchDate - today;
    let days = Math.floor(diff / (1000 * 60 * 60 * 24));
    let hours = Math.floor((diff % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
    let minutes = Math.floor((diff % (1000 * 60 * 60)) / (1000 * 60));
    let seconds = Math.floor((diff % (1000 * 60)) / 1000);
    document.getElementById("timer").innerHTML =
        "<div class=\"days\"> \
        <div class=\"numbers\">" + days + "</div>days</div> \
        <div class=\"hours\"> \
        <div class=\"numbers\">" + hours + "</div>hours</div> \
        <div class=\"minutes\"> \
        <div class=\"numbers\">" + minutes + "</div>mins</div> \
        <div class=\"seconds\"> \
        <div class=\"numbers\">" + seconds + "</div>secs</div> \
        </div>";
}, 1000);