Changing the 1-24 hour to 1-12 hour for the “getHours()” Method

Question

When I use the \"getHour()\" method in javascript, it displays the military time format. I need it to display the hour in numbers between 1-12 instead. Can anybody tell me

Answer 1

Other answers are indeed very good. But I think, following can be included too.

var d = new Date();
var hour = d.getHours(); 
var minute = d.getMinutes();
var fulltime = "";

// create a 24 elements(0-23) array containing following values
const arrayHrs = [12,1,2,3,4,5,6,7,8,9,10,11,12,1,2,3,4,5,6,7,8,9,10,11];

    // since getMinutes() returns 0 to 9 for upto 9 minutes, not 00 to 09, we can do this
    if(minute < 10) {
        minute = "0" + minute;
    }

    if( hour < 12) {
        // Just for an example, if hour = 11 and minute = 29
        fulltime = arrayHrs[hour] + ":" + minute + " AM"; // fulltime = 11:29 AM
    }
    else {
        // similarly, if hour = 22 and minute = 8
        fulltime = arrayHrs[hour] + ":" + minute + " PM"; // fulltime = 10:08 PM
    }

See what I did there in arrayHrs ;)

Answer 2

getDateTime = () => {
    const today = new Date();
    const day = today.toLocaleDateString('en-us', { weekday: 'short' });
    const month = today.toLocaleString('en-us', { month: 'short' });
    const date = today.getDate()
    const year = today.getFullYear()
    const hours = today.getHours()
    const minutes = today.getMinutes().toString()
    var dayORnight = "AM";
    if (hours > 11) { dayORnight = "PM"; }
    if (hours > 12) { hours = hours - 12; }
    if (hours == 0) { hours = 12; }
    if (hours < 10) { hours = "0" + hours; }
    if (minutes < 10) { minutes = "0" + minutes; }

    const datetime = `${day}, ${month} ${date}, ${year} at ${hours}:${minutes} ${dayORnight}`;
    console.log(datetime)
}

Answer 3

An answer similar to the accepted, but without the || operator.

Purely arithmetical:

// returns the hours number for a date, between 1 and 12
function hours12(date) { return (date.getHours() + 11) % 12 + 1; }

Test it here. Simulating hours 0 - 23:

var demoTable = document.getElementById("demo");

// simulate getHours() values 0-23
for (i = 0; i < 24; i++) {
  var row = demoTable.insertRow(-1);
  var format24Cell = row.insertCell(0);
  var conversionCell = row.insertCell(1);
  var format12Cell = row.insertCell(2);
  format24Cell.innerHTML = i;
  conversionCell.innerHTML = "( <b>" + i + "</b> + 11) % 12 + 1 =";
  
  // conversion takes place here
  format12Cell.innerHTML = (i + 11) % 12 + 1;
}

table {
  border-collapse: collapse;
  width: 100%;
}

table,
th,
td {
  border: 1px solid black;
}

th {
  padding: 0, 5px
}

td {
  padding-left: 5px;
}

<table id="demo">
  <tr>
    <th colspan="3">24 to 12 Hour Format Conversion Demo</th>
  <tr>
  <tr>
    <th>24 Hour Format</th>
    <th>Conversion</th>
    <th>12 Hour Format</th>
  </tr>
</table>

Answer 4

Why not do it the brief way? Math, people! :)

// returns the hours number for a date, between 1 and 12
function hours12(date) { return (date.getHours() + 24) % 12 || 12; }

Answer 5

Shortest:

const hours12 = date => (date.getHours() % 12  || 12);

If you need padding with 0:

const hours12 = date => ("0"+(date.getHours() % 12  || 12)).slice(-2);

Another option, also with AM & PM:

const hours12 = date => date.toLocaleString('en-US', { hour: 'numeric', hour12: true })

Answer 6

This will correct 13 - 24 back to the range 1 - 12, and 0 back to 12:

var hours = time.getHours();
if (hours > 12) {
    hours -= 12;
} else if (hours === 0) {
   hours = 12;
}

Also, you need to stop repeating yourself in your code. Call time.getHours() and time.getMinutes() and store their values just once each, and then worry about adding the leading zeroes, e.g.:

function updateclock() {

    function pad(n) {
         return (n < 10) ? '0' + n : n;
    }

    var time = new Date();
    var hours = time.getHours();
    var minutes = time.getMinutes();

    if (hours > 12) {
        hours -= 12;
    } else if (hours === 0) {
        hours = 12;
    }

    var todisplay = pad(hours) + ':' + pad(minutes);
    document.getElementById("clock").innerHTML = todisplay;
}