JavaScript padStart alternative

main.js

if (require.main === module) {
  main()
}

async function main () {
  try {
    const value = 1234
    const str = value.toString(16)
    const expected = '0x' + str.padStart(4, '0')

    const step1 = '000' + str // <1>
    const step2 = step1.slice(-4) // <2>
    const step3 = '0x' + step2 // <3>

    const actual = step3
    // const actual = '0x' + ('000' + str).slice(-4)

    console.log({expected, actual})
  } catch (err) {
    console.error(err)
  }
}