Sometimes, we want to prepend a zero in front of any number below 10 in JavaScript.

In this article, we’ll look at how to prepend a zero in front of any number below 10 in JavaScript.

How to prepend a zero in front of any number below 10 in JavaScript?

To prepend a zero in front of any number below 10 in JavaScript, we can use the JavaScript string’s padStart method.

For instance, we write:

const m = (5).toString().padStart(2, '0')
const n = (100).toString().padStart(2, '0')
console.log(m, n)

to convert 5 to a string with toString and then call padStart to pad the string to length 2 by prepending '0' onto it.

Then we assign the returned string to m.

Likewise, we try to the same thing with 100.

As a result, we see '05' and '100' logged.

Conclusion

To prepend a zero in front of any number below 10 in JavaScript, we can use the JavaScript string’s padStart method.