HEX2BIN.js

// Copyright (c) 2012 Sutoiku, Inc. (MIT License)

function HEX2BIN(number, places) {  
  // Return error if number is not hexadecimal or contains more than ten characters (10 digits)
  if (!/^[0-9A-Fa-f]{1,10}$/.test(number)) return '#NUM!';

  // Check if number is negative
  var negative = (number.length === 10 && number.substring(0, 1).toLowerCase() === 'f') ? true : false;
  
  // Convert hexadecimal number to decimal
  var decimal = (negative) ? parseInt(number, 16) - 1099511627776 : parseInt(number, 16);

  // Return error if number is lower than -512 or greater than 511
  if (decimal < -512 || decimal > 511) return '#NUM!';

  // Ignore places and return a 10-character binary number if number is negative
  if (negative) return '1' + _s.repeat('0', 9 - (512 + decimal).toString(2).length) + (512 + decimal).toString(2);

  // Convert decimal number to binary
  var result = decimal.toString(2);

  // Return binary number using the minimum number of characters necessary if places is undefined
  if (typeof places === 'undefined') {
    return result;
  } else {
    // Return error if places is nonnumeric
    if (isNaN(places)) return '#VALUE!';
    
    // Return error if places is negative
    if (places < 0) return '#NUM!';
    
    // Truncate places in case it is not an integer
    places = Math.floor(places);

    // Pad return value with leading 0s (zeros) if necessary (using Underscore.string)
    return (places >= result.length) ? _s.repeat('0', places - result.length) + result : '#NUM!';
  }
}