Simplest way to add a leading zero to a number in Javascript

#javascript #programming #webdev #ui

The simplest way to pad a number with leading zero is to use padStart() method provides by Javascript. We can use this for numbers less than 10.

Syntax



string.padStart(targetLength, padString)

Parameters

targetLength: length of the final string
padstring: string you want to pad/add to given number.

Example



const number = 9;
console.log(number.toString().padStart(2, '0'))
//Output: 09

Alternatively use can also use:

1.slice() method
In this method, we add a zero to the number and slice to extract 2 digit value of the result. We use negative value to select from end of the string.



const number = 9;
console.log(("0" + number).slice(-2))
//Output: 09

2. if check for numbers less than 10



const number = 9;
if(number< 10){
console.log("0" + number);
}
else{
console.log(number)
}
//Output: 09

Use case: When you want to display timer in your web application. You need to pad leading zero to minutes and seconds less than 10.

How I fixed 20 seconds of lag for every user in just 20 minutes.

Our AI agent was running 10-20 seconds slower than it should, impacting both our own developers and our early adopters. See how I used Sentry Profiling to fix it in record time.