padStart is not a function

Question

let m = 5;
m = m.padStart(2, '0');

Error:

m.padStart is not a function

Expecting result: 05;

I'm on Chrome, last version.

Any help?

It's a string method, so if you want to use it, cast the number to a string. — CertainPerformance, Jan 05 '19 at 08:21

ellipsis · Accepted Answer · 2019-01-05T08:21:25.180

15

The padStart() method pads the current string with another string (multiple times, if needed) until the resulting string reaches the given length. The padding is applied from the start (left) of the current string.

It is a String function. Not a number function. Refer

Solution-

let m = '5';
m = m.padStart(2, '0');
alert(m)

edited Jan 05 '19 at 08:21

answered Jan 05 '19 at 08:19

ellipsis

12,049
2
17
33

and what IS method for numbers? – qadenza Jan 05 '19 at 08:21
You have to convert number to string. Refer--https://stackoverflow.com/questions/10073699/pad-a-number-with-leading-zeros-in-javascript – ellipsis Jan 05 '19 at 08:23
2

There seems to be a reason why `m` is a number, hence I would leave that as it is and call `.toString()` on it before calling `.padStart()`: `m.toString().padStart(2, '0')` – Andreas Jan 05 '19 at 08:47
node 14, and i still didn't have the prototype to chain it: m.toString(...).padString is not a function. typeof m === string – MTroy Nov 01 '20 at 19:41

score 11 · Answer 2 · answered Dec 13 '19 at 06:31

11

Convert your value from int to String just like this int.toString().padStart(n, '0');

answered Dec 13 '19 at 06:31

Zoren Konte

306
4
12

This answer adds nothing to the existing answers. – warped Dec 13 '19 at 06:52

score 1 · Answer 3 · answered May 15 '19 at 01:51

change the number value to string , I was need this function to convert current hour value to leading zero number , your example should be

let m = 5+''; // just in case you can't change the actual number variable .
m = m.padStart(2, '0');

my code that i was need it

function CurrentTime(  ) {
 var today =  new Date();
  var h = today.getHours(  )+'' ; var m = today.getMinutes()+''   ;
 return  h.padStart( 2 ,  '0'  ) +':'+m.padStart( 2 ,  '0'  )  ; 
    }
 var current =  CurrentTime(  )   ;
 var timeNow = mydiv.innerText ; console.log("current: " + current)     ;

S. Mayol · Answer 4 · 2022-03-02T13:49:45.183

Since padStart() is not compatible with Internet Explorer (IE) and other old browser versions and if you try using it with numbers you can get:

let m = 5;
m = m.padStart(2, '0');
alert(m);

Uncaught TypeError: m.padStart is not a function at :2:7

Here I am to provide you a function that I created, it works fine with Strings as well as Numbers in case that somebody need something like that padding a Number to 01, 02, .. 09:

let m = 5;
m = padValue(m);
alert(m);

// Sam pading value to start with 0. eg: 01, 02, .. 09, 10, ..
function padValue(value) {
    return (value < 10) ? "0" + value : value;
}

As I mentioned you can replace assigned 5 value to 05:

let m = '5'; // The result will be 05

If you pass a value greater than 9 as String or Number will display the value without adding the padding. e.g.:

let m = '10'; // The result will be 10

Or

let m = 10; // The result will be 10

padStart is not a function

4 Answers4