How to use NumberFormat in Javascript?

Question

I'd like my countdown timer to show double digits, like "53:00" instead of "53:0". Not sure what's going wrong here? Thank you!

function convertSeconds(s) {
    var min = Math.floor(s / 60);
    var sec = s % 60;
    return nf(min, 2) + ':' + nf(sec, 2);
  }

Well that depends on whatever `nf()` is - you need to add that code to your question. — Alex K., Mar 25 '19 at 16:14
Thought that was numberformat? Do I need to make it its own function and refer to that with nf? What extra code do you expect to see? Srry, new to coding. Thanks for your time! — Pier Stein, Mar 25 '19 at 16:17
If your code works without errors then there is an `nf()` function written somewhere - in a library you have included for example, its not a built in part of JavaScript. — Alex K., Mar 25 '19 at 16:19
`nf` is not a built-in Javascript function, you will need to show where it's defined, otherwise it's impossible to tell what it is and what it does. — Etheryte, Mar 25 '19 at 16:19
Possible duplicate of [How to format numbers by prepending 0 to single-digit numbers?](https://stackoverflow.com/questions/8043026/how-to-format-numbers-by-prepending-0-to-single-digit-numbers) — feeela, Mar 25 '19 at 16:23

inorganik · Answer 1 · 2019-03-25T16:23:05.563

2

To pad zeroes you can do

function nf(num, places) {
  var s = '0' + num;
  return s.slice(places * -1);
}

function convertSeconds(s) {
  var min = Math.floor(s / 60);
  var sec = s % 60;
  return nf(min, 2) + ':' + nf(sec, 2);
}

Should get you what you want

edited Mar 25 '19 at 16:23

answered Mar 25 '19 at 16:16

inorganik

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1

There must be an nf() somewhere in your code stack, I would the code above with a different name as nf()'s current behavior/dependencies are unknown. – Alex K. Mar 25 '19 at 16:28

score 2 · Answer 2 · answered Mar 25 '19 at 16:20

You can use padStart() to make sure a string is a certain length. If it's not it will pad it with whatever you want. In this case 0:

const nf = (n, c) => n.toString().padStart(c, '0');

function convertSeconds(s) {
  var min = Math.floor(s / 60);
  var sec = (s % 60)
  return nf(min, 2) + ':' + nf(sec, 2);
}

console.log(convertSeconds(64))
console.log(convertSeconds(119))

Not sure if you want to pad the minutes of not.

There is also the Intl.NumberFormat() which has an option for minimum digits (though this seems like overkill for this):

console.log(new Intl.NumberFormat('en-US', { minimumIntegerDigits: 2}).format(2));

console.log(new Intl.NumberFormat('en-US', { minimumIntegerDigits: 2}).format(59));

Adnan Toky · Answer 3 · 2019-03-25T16:30:35.493

1

The nf() function should be like this:

function nf(num){
    if(num < 10){
        return "0"+num;
    }
    return num;
}

console.log(nf(7));
// 07
console.log(nf(11));
// 11

edited Mar 25 '19 at 16:30

answered Mar 25 '19 at 16:23

Adnan Toky

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You don't need to convert to a string for the condition. `return n <= 9 ? '0' + n : n;` will be a slightly shorter way… – feeela Mar 25 '19 at 16:25

score 1 · Answer 4 · answered Mar 25 '19 at 16:25

If by nf() you mean a function that formats a Number as string of given digits, this can be an implementation of it:

function nf(number, digits) {
  var res = number.toString();
  while (res.length < digits) {
    res = "0" + res;
  }
  return res;
}

Demo:

function convertSeconds(s) {
  var min = Math.floor(s / 60);
  var sec = s % 60;
  return nf(min, 2) + ':' + nf(sec, 2);
}

function nf(number, digits) {
  var res = number.toString();
  while (res.length < digits) {
    res = "0" + res;
  }
  return res;
}

console.log(nf(4,2));

How to use NumberFormat in Javascript?

4 Answers4