javascript - Why do I get "padStart is not a function" when using padStart on numbers? - Stack Overflow

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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?

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?

• javascript

Share Improve this question Follow edited Mar 14 at 14:53 TylerH 21.1k7878 gold badges7979 silver badges114114 bronze badges asked Jan 5, 2019 at 8:17 qadenzaqadenza 9,3011818 gold badges7878 silver badges144144 bronze badges 2

• 1 Numbers do not have a padStart method. – CertainPerformance Commented Jan 5, 2019 at 8:17
• It's a string method, so if you want to use it, cast the number to a string. – CertainPerformance Commented Jan 5, 2019 at 8:21

Add a ment  | 

4 Answers 4

Sorted by: Reset to default 20

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)

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

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)     ; 

Since padStart() is not patible 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

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