Note

Let's say you want to ensure that numbers are always represented in two digits, padding zeroes if the number is a single digit.

One way is to create a function to check if a number is less than 10 and return a string with padded zeroes.

const padZero = (num) => {
  if (num < 10) return `0${num}`
  else return `${num}`
}

console.log(padZero(3)) // 03

There's a simpler way to achieve this using JavaScript's internal method in a string called padStart.

const num = 3
console.log(num.toString().padStart(2, '0')) // 03
console.log(num.toString().padStart(3, '0')) // 003
console.log(num.toString().padStart(4, '0')) // 0003

---

Here's an example. Let's say you're working with time. We can use the above method to pad zeroes for hours, minutes, and seconds when they are less than 2 digits.

const pad = (time, count) => {
  return time.toString().padStart(count, '0')
}

const Time = ({ hour, minute, second }) => ({
  hour,
  minute,
  second,
  print() {
    return `${pad(hour, 2)}:${pad(minute, 2)}:${pad(second, 2)}`
  },
})

const date = new Date()
const currentTime = Time({
  hour: date.getHours(),
  minute: date.getMinutes(),
  second: date.getSeconds(),
})

console.log(currentTime.print())

Reference

• https://hardiquedasore.medium.com/simplest-way-to-add-a-leading-zero-to-a-number-in-javascript-b8724749486f