javascript-barcode-reader/src/code-93/index.ts

Simple & Fast Barcode decoder for Browser and Node.js

interface CharValue {
  [key: string]: string
}

const CHAR_SET: CharValue[] = [
  { '100010100': '0' },
  { '101001000': '1' },
  { '101000100': '2' },
  { '101000010': '3' },
  { '100101000': '4' },
  { '100100100': '5' },
  { '100100010': '6' },
  { '101010000': '7' },
  { '100010010': '8' },
  { '100001010': '9' },
  { '110101000': 'A' },
  { '110100100': 'B' },
  { '110100010': 'C' },
  { '110010100': 'D' },
  { '110010010': 'E' },
  { '110001010': 'F' },
  { '101101000': 'G' },
  { '101100100': 'H' },
  { '101100010': 'I' },
  { '100110100': 'J' },
  { '100011010': 'K' },
  { '101011000': 'L' },
  { '101001100': 'M' },
  { '101000110': 'N' },
  { '100101100': 'O' },
  { '100010110': 'P' },
  { '110110100': 'Q' },
  { '110110010': 'R' },
  { '110101100': 'S' },
  { '110100110': 'T' },
  { '110010110': 'U' },
  { '110011010': 'V' },
  { '101101100': 'W' },
  { '101100110': 'X' },
  { '100110110': 'Y' },
  { '100111010': 'Z' },
  { '100101110': '-' },
  { '111010100': '.' },
  { '111010010': ' ' },
  { '111001010': '$' },
  { '101101110': '/' },
  { '101110110': '+' },
  { '110101110': '%' },
  { '100100110': '($)' },
  { '111011010': '(%)' },
  { '111010110': '(/)' },
  { '100110010': '(+)' },
  { '101011110': '*' },
]

export function decoder(lines: number[]): string {
  const code = []
  const binary = []

  // remove termination bar
  lines.pop()

  const barThreshold = Math.ceil(lines.reduce((pre, item) => pre + item, 0) / lines.length)

  const minBarWidth = Math.ceil(
    lines.reduce((pre, item) => {
      if (item < barThreshold) return (pre + item) / 2
      return pre
    }, 0)
  )

  // leave the padded *
  for (let i = 0; i < lines.length; i += 1) {
    let segment = lines[i]

    while (segment > 0) {
      if (i % 2 === 0) {
        binary.push(1)
      } else {
        binary.push(0)
      }
      segment -= minBarWidth
    }
  }

  for (let i = 0; i < binary.length; i += 9) {
    const searcKey = binary.slice(i, i + 9).join('')
    const char = CHAR_SET.filter(item => Object.keys(item)[0] === searcKey)
    code.push(char[0][searcKey])
  }

  if (code.shift() !== '*' || code.pop() !== '*') return ''

  const K = code.pop()
  let sum = 0
  let letter: string
  let Value
  const findValue = (item: CharValue): boolean => Object.values(item)[0] === letter

  for (let i = code.length - 1; i >= 0; i -= 1) {
    letter = code[i]
    Value = CHAR_SET.indexOf(CHAR_SET.filter(findValue)[0])
    sum += Value * (1 + ((code.length - (i + 1)) % 20))
  }

  if (Object.values(CHAR_SET[sum % 47])[0] !== K) return ''

  const C = code.pop()
  sum = 0

  for (let i = code.length - 1; i >= 0; i -= 1) {
    letter = code[i]
    Value = CHAR_SET.indexOf(CHAR_SET.filter(findValue)[0])
    sum += Value * (1 + ((code.length - (i + 1)) % 20))
  }

  if (Object.values(CHAR_SET[sum % 47])[0] !== C) return ''

  return code.join('')
}