Code Challenge to pad zeroes to integers inside a string

codechallenge.js

//
//****************************************************************************//
//
// HOW TO RUN IT
// ------------------------------

// Open the command line and using the node.js interpreter
// $ node codechallenge.js
//
//

// SOLUTION TO THE CODE CHALLENGE
// ------------------------------
//
// 1. Split the string using a regular expression to match a group of numbers
//
// 2. Mapping over every single element of the splitted array
//
// 3. evaluate the array and operate in every item has a value of integers
//
// 4. We would only add the zeroes if the number of characters is less than the
// amount of zeroes to add
//
// 5. I found two solutions, one that uses a built-in String method `padStart`
// and another that uses a `for` loop and prepends the zeroes to the beginning
// of the string
//
// 6. Once all the parts of the splitted array had been processed, we proceed
// to join them back again
//
// ADDITIONAL INFO
// ---------------
//
// I'm using JavaScript Standard Style guide, so the semicolons can be ommitted
//
//****************************************************************************//
//

function padIntegerFromString(string, numCharacter) {
  // We can change the character from 0 to whatever we want
  const character = '0'

  // 1. Split the string using a regular expression to match a group of numbers
  let splittedArray = string.split(/(\d+)/)

  // 2. Mapping over every single element of the splitted array
  let processedArray = splittedArray.map(item => {

    // 3. evaluate the array and operate in every item has a value of integers
    if (parseInt(item, 10)) {
      const charLength = item.length

      // 4. We would only add the zeroes if the number of characters is less
      // than the amount of zeroes to add
      if (charLength < numCharacter) {

        // 5. I found two solutions, one that uses a built-in String method
        // `padStart` and another that uses a `for` loop and prepends the
        // zeroes to the beginning of the string
        //
        // --------------------------------------------//
        // => SOLUTION 1
        // --------------------------------------------//
        // Use the built-in String method `padStart`
        //
        // By commenting out the following line, and commenting in the
        // other solution
        // item = item.padStart(numCharacter, character)


        // --------------------------------------------//
        // => SOLUTION 2
        // --------------------------------------------//
        // Use a simple For loop and string concatenation
        const zeroesToAdd = numCharacter - charLength
        for (let i = 0; i < zeroesToAdd; i++) {
          item = character + item
        }

        return item
      } else {
        return item
      }
    } else {
      return item
    }
  })

  // 6. Once all the parts of the splitted array had been processed, we proceed
  // to join them back again
  return processedArray.join('')
}


//****************************************************************************//
//
// EXAMPLES
//
//****************************************************************************//

const examples = [
  ['area 59', 4],
  ['123 Foo st', 5],
  ['123 Foo st', 2],
  ['Area59asdf234', 4]
]

examples.forEach(example => {
  const exampleString = example[0]
  const numChar = example[1]

  console.log(padIntegerFromString(exampleString, numChar))
})