Generate array of times (as strings) for every X minutes in JavaScript

Question

I\'m trying to create an array of times (strings, not Date objects) for every X minutes throughout a full 24 hours. For example, for a 5 minute interval the arr

Answer 1

Manipulating with a date as with integer and using single loop:

var interval = 5 * 60 * 1000; //5 minutes 
var period = 24 * 60 * 60 * 1000; //dat period

//just converts any time to desired string
var toString = function toString(time){  
  var h = time.getHours();
  var m = time.getMinutes();
  var p = h >= 12 ? "PM" : "AM";
  h = h || 12;
  h = h > 12 ? h - 12 : h;  
  return ("0" + h).slice(-2) + ":" + ("0" + m).slice(-2) + " " + p;
}

//start time
var time = new Date(2010, 0, 1);

//resulting array
var times = [];

for ( var t = +time; t < +time + period; t += interval){  
  var d = toString(new Date(t));  
  times.push(d);
}

Answer 2

Loops are unnecessary in this case.

ES6

//Array.from, only supported by Chrome 45+, Firefox 32+, Edge and Safari 9.0+
//create an array of the expected interval
let arr = Array.from({
  length: 24 * 60 / 5
}, (v, i) => {
  let h = Math.floor(i * 5 / 60);
  let m = i * 5 - h * 60;
  //convert to 12 hours time
  //pad zero to minute
  if (m < 10) {
    m = '0' + m;
  }
  let label = 'AM';
  if (h > 12) {
    label = 'PM';
    h -= 12;
  }
  if (h === 0) {
    h = 12;
  }
  return h + ':' + m + ' ' + label;
});

document.body.textContent = JSON.stringify(arr);

Wider browser support

var arr = Array.apply(null, {
  length: 24 * 60 / 5
}).map(function(v, i) {
  var h = Math.floor(i * 5 / 60);
  var m = i * 5 - h * 60;
  if (m < 10) {
    m = '0' + m;
  }
  var label = 'AM';
  if (h > 12) {
    label = 'PM';
    h -= 12;
  }
  if (h === 0) {
    h = 12;
  }
  return h + ':' + m + ' ' + label;
});

document.body.textContent = JSON.stringify(arr);

Answer 3

const getTimes = (increment = 2) => {
  const times = [];
  for (let i = 0; i < 24; i++) {
    times.push({
      value: `${i === 0 || i - 12 === 0 ? 12 : i < 12 ? i : i - 12}:00 ${i < 12 ? 'AM' : 'PM'}`,
      label: `${i === 0 || i - 12 === 0 ? 12 : i < 12 ? i : i - 12}:00 ${i < 12 ? 'AM' : 'PM'}`,
    });
    for (let j = 60 / increment; j < 60; j += 60 / increment) {
      times.push({
        value: `${i === 0 || i - 12 === 0 ? 12 : i < 12 ? i : i - 12}:${Math.ceil(j)} ${i < 12 ? 'AM' : 'PM'}`,
        label: `${i === 0 || i - 12 === 0 ? 12 : i < 12 ? i : i - 12}:${Math.ceil(j)} ${i < 12 ? 'AM' : 'PM'}`,
      });
    }
  }
  return times;
};

Answer 4

if you have access to moment, you can always do something like this:

const locale = 'en'; // or whatever you want...
const hours = [];

moment.locale(locale);  // optional - can remove if you are only dealing with one locale

for(let hour = 0; hour < 24; hour++) {
    hours.push(moment({ hour }).format('h:mm A'));
    hours.push(
        moment({
            hour,
            minute: 30
        }).format('h:mm A')
    );
}

the result is the following array:

["12:00 AM", "12:30 AM", "1:00 AM", "1:30 AM", "2:00 AM", "2:30 AM", "3:00 AM", "3:30 AM", "4:00 AM", "4:30 AM", "5:00 AM", "5:30 AM", "6:00 AM", "6:30 AM", "7:00 AM", "7:30 AM", "8:00 AM", "8:30 AM", "9:00 AM", "9:30 AM", "10:00 AM", "10:30 AM", "11:00 AM", "11:30 AM", "12:00 PM", "12:30 PM", "1:00 PM", "1:30 PM", "2:00 PM", "2:30 PM", "3:00 PM", "3:30 PM", "4:00 PM", "4:30 PM", "5:00 PM", "5:30 PM", "6:00 PM", "6:30 PM", "7:00 PM", "7:30 PM", "8:00 PM", "8:30 PM", "9:00 PM", "9:30 PM", "10:00 PM", "10:30 PM", "11:00 PM", "11:30 PM"]

Answer 5

My solution with emphasize on readability. It first creates objects that represent correct times and then formats them to strings. JsFiddle https://jsfiddle.net/6qk60hxs/

var periods = ['AM', 'PM'];
var hours = [12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
var minutes = ["00", "05", 10, 15, 20, 25, 30, 35, 40, 45, 50, 55];


timeObj = add([{}], "p", periods);
timeObj = add(timeObj, "h", hours);
timeObj = add(timeObj, "m", minutes);

times = []
for (t of timeObj) {
  times.push(t.h + ':' + t.m + ' ' + t.p);
}

console.log(times)

function add(tab, prop, val) {
  var result = [];
  for (t of tab) {
    for (v of val) {
      tc = _.clone(t);
      tc[prop] = v;
      result.push(tc);
    }
  }
  return result
}

Answer 6

If the interval is only to be set in minutes[0-60], then evaluate the below solution w/o creating the date object and in single loop:

var x = 5; //minutes interval
var times = []; // time array
var tt = 0; // start time
var ap = ['AM', 'PM']; // AM-PM

//loop to increment the time and push results in array
for (var i=0;tt<24*60; i++) {
  var hh = Math.floor(tt/60); // getting hours of day in 0-24 format
  var mm = (tt%60); // getting minutes of the hour in 0-55 format
  times[i] = ("0" + (hh % 12)).slice(-2) + ':' + ("0" + mm).slice(-2) + ap[Math.floor(hh/12)]; // pushing data in array in [00:00 - 12:00 AM/PM format]
  tt = tt + x;
}

console.log(times);