Validate ABN - (Australian Business Number)

validate_abn.ts

function validateABN(abn: string): boolean {
  /*
  @name: validateABN
  @param {string} abn
  @returns {boolean} 
  @link https://abr.business.gov.au/Help/AbnFormat
  */
  const weightingFactors = [10, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19]
  const cleanedABN = abn.replace(/\s/g, '')

  if (cleanedABN.length !== 11) {
    return false
  }

  let sum = 0
  for (let i = 0; i < 11; i++) {
    sum += (parseInt(cleanedABN[i]) - (i === 0 ? 1 : 0)) * weightingFactors[i]
  }

  return sum % 89 === 0
}