Native JS Implementation Countdown

HTML code:

<div class= "box" > Distance from work and:<span>01:01:30</span></div>

CSS code:

*{
    margin:0;
    padding:0;
}
. box{
    width:600px;
    height:40px;
    margin:30px Auto;
    Text-align:center;
    line-height:40px;
    font-size:26px;
    Font-weight:bold;
    border:2px dashed darkred;
    Background:lightcyan;
}
. Box span{
    padding-left:10px;
    Color:darkblue;
}
JS Code:
var span =

Document.getelementsbyclassname (' box ') [0].getelementsbytagname (' span ') [0];

var timer = window.setinterval (record,1000);
function record () {
var curdate = new Date ();//Gets the current time

var targetdate = new Date (' 2016/09/22 18:14:00 '); Target time, first converted to a time-formatted object to use the GetTime () method
var curDate1970 = Curdate.gettime (); Number of MS in current time distance 1970
var targetDate1970 = Targetdate.gettime (); Target distance of 1970 MS
var time = targetdate1970-curdate1970; Time difference
Conversion units convert time to h/m/s
Convert to hours first
var h = Math.floor (time/(1000*60*60)); Rounding down
Conversion minutes  = The number of MS that is occupied by H hours is subtracted and then converted to minutes
var m = Math.floor ((time-h*60*60*1000)/(1000*60));
convert s  = Subtract the number of MS that is occupied by hours and minutes, and then convert it to S
var s = Math.floor ((time-h*60*60*1000-m*60*1000)/1000);
if (H + m + s <= 0) {
    Window.clearinterval (timer);
    span.innerhtml = "00:00:00"
    Return
}
span.innerhtml = Addzero (h) + ":" + Addzero (m) + ":" + Addzero (s);
}

function Addzero (n) {//Add a 0 before the number less than 10
    return N < 10? ' 0 ' + n ';
}

Date.gettime (); The current date time is the number of milliseconds from 8 o'clock January 1, 1970.

Note: var date2 = new Date (' 2016/09/24 17:00:00 ');
Console.log (DATE2);
If a time-format string is added to the parentheses during new, the string is converted to a time object. Then you can use the getFullYear () method.
Date2.getfullyear ();

Native JS Implementation Countdown