bank-ocr.js

var PATTERNS = {
  0: [" _ ",
      "| |",
      "|_|",
      "   "],
  1: ["   ",
      "  |",
      "  |",
      "   "],
  2: [" _ ",
      " _|",
      "|_ ",
      "   "],
  3: [" _ ",
      " _|",
      " _|",
      "   "],
  4: ["   ",
      "|_|",
      "  |",
      "   "],
  5: [" _ ",
      "|_ ",
      " _|",
      "   "],
  6: [" _ ",
      "|_ ",
      "|_|",
      "   "],
  7: [" _ ",
      "  |",
      "  |",
      "   "],
  8: [" _ ",
      "|_|",
      "|_|",
      "   "],
  9: [" _ ",
      "|_|",
      " _|",
      "   "]
};

exports.convert = function(text) {
  var entries = [];
  var lines = text.split("\n");
  for (var entryNumber = 0; entryNumber < lines.length; entryNumber += 4) {
    var entry = '';
    for (var entryLine = 0; entryLine < 4; entryLine++) {
      entry += lines[entryNumber + entryLine] + "\n";
    }
    entries.push(entry);
  }

  return entries.map(function(entry) {
    var patterns = [];
    var lines = entry.split('\n');
    for (var patternNumber = 0; patternNumber < lines[0].length; patternNumber += 3) {
      var pattern = '';
      for (var lineNumber = 0; lineNumber < lines.length; lineNumber++) {
        pattern += lines[lineNumber].substr(patternNumber, 3);
      }
      patterns.push(pattern);
    }

    var accountNumber = patterns.map(function(pattern) {
      for (var digit in PATTERNS) {
        if (PATTERNS[digit].join('') === pattern) {
          return digit;
        }
      }
      return '?';
    }).join('');

    if (accountNumber.indexOf('?') !== -1) {
      return accountNumber + ' ILL';
    } else if (!exports.isValid(accountNumber)) {
      return accountNumber + ' ERR';
    }
    return accountNumber;
  }).join('\n');
};

exports.isValid = function(accountNumber) {
  var digits = accountNumber.split('');
  var sum = 0;
  for (var i = 0; i < 9; i++) {
    sum += (9 - i) * digits[i];
  }
  return sum % 11 === 0;
};