Часы №3

<div id="clock">
    <div id="info">
        <div id="time"></div>
        <div id="date"></div>
    </div>
    <div id="controls">
        <span id="slider">
            <div id="slider1"></div>
            <div id="slider2"></div>
        </span>
    </div>
</div>

@import url("https://fonts.googleapis.com/css?family=Roboto:300,400,500,700");
body {
    font-family: "Roboto", sans-serif;
}

#clock {
    color: white;
    display: -webkit-box;
    display: -webkit-flex;
    display: -moz-box;
    display: flex;
    -webkit-flex-wrap: wrap;
    flex-wrap: wrap;
    -webkit-box-align: center;
    -webkit-align-items: center;
    -moz-box-align: center;
    align-items: center;
    -webkit-box-pack: center;
    -webkit-justify-content: center;
    -moz-box-pack: center;
    justify-content: center;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
    -webkit-animation: fadeIn 1s ease-in-out;
    -moz-animation: fadeIn 1s ease-in-out;
    -o-animation: fadeIn 1s ease-in-out;
    animation: fadeIn 1s ease-in-out;
    cursor: pointer;
    -webkit-border-radius: 2em;
    -moz-border-radius: 2em;
    border-radius: 2em;
    padding: 0.5em 1em;
    -webkit-backface-visibility: hidden;
    -moz-backface-visibility: hidden;
    backface-visibility: hidden;
    -webkit-transition: all 0.5s;
    -o-transition: all 0.5s;
    -moz-transition: all 0.5s;
    transition: all 0.5s;
}
#clock:hover {
    background: #8e44ad;
}
#clock #info {
    width: 100%;
}
#clock #info #time {
    font-size: 6em;
    display: inline-block;
}
#clock #info #date {
    margin-top: 1.8em;
    margin-bottom: 0.2em;
    font-size: 2em;
    display: inline-block;
}

@-webkit-keyframes fadeIn {
    0% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}

@-moz-keyframes fadeIn {
    0% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}

@-o-keyframes fadeIn {
    0% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}

@keyframes fadeIn {
    0% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}
#controls #slider {
    display: block;
    cursor: pointer;
    width: 2em;
    height: 1.5em;
    -webkit-transition: 0.25s;
    -o-transition: 0.25s;
    -moz-transition: 0.25s;
    transition: 0.25s;
    position: relative;
}
#controls #slider div {
    position: absolute;
    content: "";
    height: 0.5em;
    width: 0.5em;
    left: 4px;
    bottom: 4px;
    background-color: white;
    -webkit-border-radius: 50%;
    -moz-border-radius: 50%;
    border-radius: 50%;
    -webkit-transition: 0.25s;
    -o-transition: 0.25s;
    -moz-transition: 0.25s;
    transition: 0.25s;
}
#controls #slider #slider2 {
    -webkit-transform: translateX(1em);
    -moz-transform: translateX(1em);
    -o-transform: translateX(1em);
    transform: translateX(1em);
    opacity: 0.5;
}

@media screen and (max-width: 750px) {
    #clock #info #time {
        font-size: 4.5em;
    }
    #clock #info #date {
        font-size: 1.5em;
    }
}
@media screen and (max-width: 450px) {
    #clock #info #time {
        font-size: 3em;
    }
    #clock #info #date {
        font-size: 1em;
    }
}

let hours24 = true;
const clock = document.querySelector("#clock");
clock.addEventListener("click", toggleFormat);

function toggleFormat() {
    const slider1 = document.getElementById("slider1");
    const slider2 = document.getElementById("slider2");
    hours24 = !hours24;
    if (hours24 == true) {
        slider1.style.opacity = 1;
        slider2.style.opacity = 0.5;
    } else {
        slider1.style.opacity = 0.5;
        slider2.style.opacity = 1;
    }
    displayClock();
}

function getTime(date, hourChange, suffix) {
    const hours = date.getHours() - hourChange;
    const minutes = ("0" + date.getMinutes()).slice(-2);
    const time = `${hours}:${minutes}${suffix}`;
    return time;
}

function getFormattedTime(date) {
    if (hours24 == false) {
        if (date.getHours() < 12) {
            return getTime(date, 0, "дп");
        } else if (date.getHours() == 12) {
            return getTime(date, 0, "пп");
        } else {
            return getTime(date, 12, "пп");
        }
    } else {
        return getTime(date, 0, "");
    }
}

function displayClock() {
    const months = ["янв", "фев", "мар", "апр", "мая", "июн", "июл", "авг", "сен", "окт", "ноя", "дек"];
    const date = new Date();
    const time = getFormattedTime(date);
    const shortDate = `${date.getDate()} - ${months[date.getMonth()]}`;

    document.getElementById("time").textContent = time;
    document.getElementById("date").textContent = shortDate;
}

function startClock() {
    displayClock();
    setInterval(displayClock, 1000);
}

startClock();