Live time and date with JavaScript

Use cases are rare but displaying the live time on a webpage is a neat feature, perhaps for a dashboard or panel would it suit best.

There is no need for Jquery just pure vanilla JavaScript and some defined HTML spans.

Base code is 12 hour time with AM/PM and the date says the day (name), month and day (number). These of course can be changed.

HTML elements to display the live time and date:

<span class="hours_mins_secs"></span>
<span class="am_pm"></span>
<br>
<span class="date"></span>

And the Javascript code is:

function liveTime() {
    var dateInfo = new Date();
    var hr,
        _min = (dateInfo.getMinutes() < 10) ? "0" + dateInfo.getMinutes() : dateInfo.getMinutes(), //If less than 10 add 0 onto front 1 -> 01
        sec = (dateInfo.getSeconds() < 10) ? "0" + dateInfo.getSeconds() : dateInfo.getSeconds(),
        am_pm = (dateInfo.getHours() >= 12) ? "PM" : "AM"; //Decide if AM or PM
    if (dateInfo.getHours() == 0) { //24hr to 12 hour calculations
        hr = 12;
    } else if (dateInfo.getHours() > 12) {
        hr = dateInfo.getHours() - 12;
    } else {
        hr = dateInfo.getHours();
    }
    var currentTime = hr + ":" + _min + ":" + sec;
    document.getElementsByClassName("hours_mins_secs")[0].innerHTML = currentTime; //hh:mm:ss element
    document.getElementsByClassName("am_pm")[0].innerHTML = am_pm; //AM or PM element
    var day_name = [
            "Sunday",
            "Monday",
            "Tuesday",
            "Wednesday",
            "Thursday",
            "Friday",
            "Saturday"
        ],
        month = [
            "January",
            "February",
            "March",
            "April",
            "May",
            "June",
            "July",
            "August",
            "September",
            "October",
            "November",
            "December"
        ],
        day = dateInfo.getDate();
    var currentDate = day_name[dateInfo.getDay()] + ", " + month[dateInfo.getMonth()] + " " + day; //replaces int with string. Day = 2 is Tuesday
    document.getElementsByClassName("date")[0].innerHTML = currentDate; //Date element
};
liveTime();
setInterval(function() {
    liveTime()
}, 1000); //1 second updates