(function(global) {
  'use strict';

  var nativeKeyboardEvent = ('KeyboardEvent' in global);
  if (!nativeKeyboardEvent)
    global.KeyboardEvent = function KeyboardEvent() { throw TypeError('Illegal constructor'); };

  [
    ['DOM_KEY_LOCATION_STANDARD', 0x00], // Default or unknown location
    ['DOM_KEY_LOCATION_LEFT', 0x01], // e.g. Left Alt key
    ['DOM_KEY_LOCATION_RIGHT', 0x02], // e.g. Right Alt key
    ['DOM_KEY_LOCATION_NUMPAD', 0x03], // e.g. Numpad 0 or +
  ].forEach(function(p) { if (!(p[0] in global.KeyboardEvent)) global.KeyboardEvent[p[0]] = p[1]; });

  var STANDARD = global.KeyboardEvent.DOM_KEY_LOCATION_STANDARD,
      LEFT = global.KeyboardEvent.DOM_KEY_LOCATION_LEFT,
      RIGHT = global.KeyboardEvent.DOM_KEY_LOCATION_RIGHT,
      NUMPAD = global.KeyboardEvent.DOM_KEY_LOCATION_NUMPAD;

  //--------------------------------------------------------------------
  //
  // Utilities
  //
  //--------------------------------------------------------------------

  function contains(s, ss) { return String(s).indexOf(ss) !== -1; }

  var os = (function() {
    if (contains(navigator.platform, 'Win')) { return 'win'; }
    if (contains(navigator.platform, 'Mac')) { return 'mac'; }
    if (contains(navigator.platform, 'CrOS')) { return 'cros'; }
    if (contains(navigator.platform, 'Linux')) { return 'linux'; }
    if (contains(navigator.userAgent, 'iPad') || contains(navigator.platform, 'iPod') || contains(navigator.platform, 'iPhone')) { return 'ios'; }
    return '';
  } ());

  var browser = (function() {
    if (contains(navigator.userAgent, 'Chrome/')) { return 'chrome'; }
    if (contains(navigator.vendor, 'Apple')) { return 'safari'; }
    if (contains(navigator.userAgent, 'MSIE')) { return 'ie'; }
    if (contains(navigator.userAgent, 'Gecko/')) { return 'moz'; }
    if (contains(navigator.userAgent, 'Opera/')) { return 'opera'; }
    return '';
  } ());

  var browser_os = browser + '-' + os;

  function mergeIf(baseTable, select, table) {
    if (browser_os === select || browser === select || os === select) {
      Object.keys(table).forEach(function(keyCode) {
        baseTable[keyCode] = table[keyCode];
      });
    }
  }

  function remap(o, key) {
    var r = {};
    Object.keys(o).forEach(function(k) {
      var item = o[k];
      if (key in item) {
        r[item[key]] = item;
      }
    });
    return r;
  }

  function invert(o) {
    var r = {};
    Object.keys(o).forEach(function(k) {
      r[o[k]] = k;
    });
    return r;
  }

  //--------------------------------------------------------------------
  //
  // Generic Mappings
  //
  //--------------------------------------------------------------------

  // "keyInfo" is a dictionary:
  //   code: string - name from UI Events KeyboardEvent code Values
  //     https://w3c.github.io/uievents-code/
  //   location (optional): number - one of the DOM_KEY_LOCATION values
  //   keyCap (optional): string - keyboard label in en-US locale
  // USB code Usage ID from page 0x07 unless otherwise noted (Informative)

  // Map of keyCode to keyInfo
  var keyCodeToInfoTable = {
    // 0x01 - VK_LBUTTON
    // 0x02 - VK_RBUTTON
    0x03: { code: 'Cancel' }, // [USB: 0x9b] char \x0018 ??? (Not in D3E)
    // 0x04 - VK_MBUTTON
    // 0x05 - VK_XBUTTON1
    // 0x06 - VK_XBUTTON2
    0x06: { code: 'Help' }, // [USB: 0x75] ???
    // 0x07 - undefined
    0x08: { code: 'Backspace' }, // [USB: 0x2a] Labelled Delete on Macintosh keyboards.
    0x09: { code: 'Tab' }, // [USB: 0x2b]
    // 0x0A-0x0B - reserved
    0X0C: { code: 'Clear' }, // [USB: 0x9c] NumPad Center (Not in D3E)
    0X0D: { code: 'Enter' }, // [USB: 0x28]
    // 0x0E-0x0F - undefined

    0x10: { code: 'Shift' },
    0x11: { code: 'Control' },
    0x12: { code: 'Alt' },
    0x13: { code: 'Pause' }, // [USB: 0x48]
    0x14: { code: 'CapsLock' }, // [USB: 0x39]
    0x15: { code: 'KanaMode' }, // [USB: 0x88]
    0x16: { code: 'Lang1' }, // [USB: 0x90]
    // 0x17: VK_JUNJA
    // 0x18: VK_FINAL
    0x19: { code: 'Lang2' }, // [USB: 0x91]
    // 0x1A - undefined
    0x1B: { code: 'Escape' }, // [USB: 0x29]
    0x1C: { code: 'Convert' }, // [USB: 0x8a]
    0x1D: { code: 'NonConvert' }, // [USB: 0x8b]
    0x1E: { code: 'Accept' }, // [USB: ????]
    0x1F: { code: 'ModeChange' }, // [USB: ????]

    0x20: { code: 'Space' }, // [USB: 0x2c]
    0x21: { code: 'PageUp' }, // [USB: 0x4b]
    0x22: { code: 'PageDown' }, // [USB: 0x4e]
    0x23: { code: 'End' }, // [USB: 0x4d]
    0x24: { code: 'Home' }, // [USB: 0x4a]
    0x25: { code: 'ArrowLeft' }, // [USB: 0x50]
    0x26: { code: 'ArrowUp' }, // [USB: 0x52]
    0x27: { code: 'ArrowRight' }, // [USB: 0x4f]
    0x28: { code: 'ArrowDown' }, // [USB: 0x51]
    0x29: { code: 'Select' }, // (Not in D3E)
    0x2A: { code: 'Print' }, // (Not in D3E)
    0x2B: { code: 'Execute' }, // [USB: 0x74] (Not in D3E)
    0x2C: { code: 'PrintScreen' }, // [USB: 0x46]
    0x2D: { code: 'Insert' }, // [USB: 0x49]
    0x2E: { code: 'Delete' }, // [USB: 0x4c]
    0x2F: { code: 'Help' }, // [USB: 0x75] ???

    0x30: { code: 'Digit0', keyCap: '0' }, // [USB: 0x27] 0)
    0x31: { code: 'Digit1', keyCap: '1' }, // [USB: 0x1e] 1!
    0x32: { code: 'Digit2', keyCap: '2' }, // [USB: 0x1f] 2@
    0x33: { code: 'Digit3', keyCap: '3' }, // [USB: 0x20] 3#
    0x34: { code: 'Digit4', keyCap: '4' }, // [USB: 0x21] 4$
    0x35: { code: 'Digit5', keyCap: '5' }, // [USB: 0x22] 5%
    0x36: { code: 'Digit6', keyCap: '6' }, // [USB: 0x23] 6^
    0x37: { code: 'Digit7', keyCap: '7' }, // [USB: 0x24] 7&
    0x38: { code: 'Digit8', keyCap: '8' }, // [USB: 0x25] 8*
    0x39: { code: 'Digit9', keyCap: '9' }, // [USB: 0x26] 9(
    // 0x3A-0x40 - undefined

    0x41: { code: 'KeyA', keyCap: 'a' }, // [USB: 0x04]
    0x42: { code: 'KeyB', keyCap: 'b' }, // [USB: 0x05]
    0x43: { code: 'KeyC', keyCap: 'c' }, // [USB: 0x06]
    0x44: { code: 'KeyD', keyCap: 'd' }, // [USB: 0x07]
    0x45: { code: 'KeyE', keyCap: 'e' }, // [USB: 0x08]
    0x46: { code: 'KeyF', keyCap: 'f' }, // [USB: 0x09]
    0x47: { code: 'KeyG', keyCap: 'g' }, // [USB: 0x0a]
    0x48: { code: 'KeyH', keyCap: 'h' }, // [USB: 0x0b]
    0x49: { code: 'KeyI', keyCap: 'i' }, // [USB: 0x0c]
    0x4A: { code: 'KeyJ', keyCap: 'j' }, // [USB: 0x0d]
    0x4B: { code: 'KeyK', keyCap: 'k' }, // [USB: 0x0e]
    0x4C: { code: 'KeyL', keyCap: 'l' }, // [USB: 0x0f]
    0x4D: { code: 'KeyM', keyCap: 'm' }, // [USB: 0x10]
    0x4E: { code: 'KeyN', keyCap: 'n' }, // [USB: 0x11]
    0x4F: { code: 'KeyO', keyCap: 'o' }, // [USB: 0x12]

    0x50: { code: 'KeyP', keyCap: 'p' }, // [USB: 0x13]
    0x51: { code: 'KeyQ', keyCap: 'q' }, // [USB: 0x14]
    0x52: { code: 'KeyR', keyCap: 'r' }, // [USB: 0x15]
    0x53: { code: 'KeyS', keyCap: 's' }, // [USB: 0x16]
    0x54: { code: 'KeyT', keyCap: 't' }, // [USB: 0x17]
    0x55: { code: 'KeyU', keyCap: 'u' }, // [USB: 0x18]
    0x56: { code: 'KeyV', keyCap: 'v' }, // [USB: 0x19]
    0x57: { code: 'KeyW', keyCap: 'w' }, // [USB: 0x1a]
    0x58: { code: 'KeyX', keyCap: 'x' }, // [USB: 0x1b]
    0x59: { code: 'KeyY', keyCap: 'y' }, // [USB: 0x1c]
    0x5A: { code: 'KeyZ', keyCap: 'z' }, // [USB: 0x1d]
    0x5B: { code: 'MetaLeft', location: LEFT }, // [USB: 0xe3]
    0x5C: { code: 'MetaRight', location: RIGHT }, // [USB: 0xe7]
    0x5D: { code: 'ContextMenu' }, // [USB: 0x65] Context Menu
    // 0x5E - reserved
    0x5F: { code: 'Standby' }, // [USB: 0x82] Sleep

    0x60: { code: 'Numpad0', keyCap: '0', location: NUMPAD }, // [USB: 0x62]
    0x61: { code: 'Numpad1', keyCap: '1', location: NUMPAD }, // [USB: 0x59]
    0x62: { code: 'Numpad2', keyCap: '2', location: NUMPAD }, // [USB: 0x5a]
    0x63: { code: 'Numpad3', keyCap: '3', location: NUMPAD }, // [USB: 0x5b]
    0x64: { code: 'Numpad4', keyCap: '4', location: NUMPAD }, // [USB: 0x5c]
    0x65: { code: 'Numpad5', keyCap: '5', location: NUMPAD }, // [USB: 0x5d]
    0x66: { code: 'Numpad6', keyCap: '6', location: NUMPAD }, // [USB: 0x5e]
    0x67: { code: 'Numpad7', keyCap: '7', location: NUMPAD }, // [USB: 0x5f]
    0x68: { code: 'Numpad8', keyCap: '8', location: NUMPAD }, // [USB: 0x60]
    0x69: { code: 'Numpad9', keyCap: '9', location: NUMPAD }, // [USB: 0x61]
    0x6A: { code: 'NumpadMultiply', keyCap: '*', location: NUMPAD }, // [USB: 0x55]
    0x6B: { code: 'NumpadAdd', keyCap: '+', location: NUMPAD }, // [USB: 0x57]
    0x6C: { code: 'NumpadComma', keyCap: ',', location: NUMPAD }, // [USB: 0x85]
    0x6D: { code: 'NumpadSubtract', keyCap: '-', location: NUMPAD }, // [USB: 0x56]
    0x6E: { code: 'NumpadDecimal', keyCap: '.', location: NUMPAD }, // [USB: 0x63]
    0x6F: { code: 'NumpadDivide', keyCap: '/', location: NUMPAD }, // [USB: 0x54]

    0x70: { code: 'F1' }, // [USB: 0x3a]
    0x71: { code: 'F2' }, // [USB: 0x3b]
    0x72: { code: 'F3' }, // [USB: 0x3c]
    0x73: { code: 'F4' }, // [USB: 0x3d]
    0x74: { code: 'F5' }, // [USB: 0x3e]
    0x75: { code: 'F6' }, // [USB: 0x3f]
    0x76: { code: 'F7' }, // [USB: 0x40]
    0x77: { code: 'F8' }, // [USB: 0x41]
    0x78: { code: 'F9' }, // [USB: 0x42]
    0x79: { code: 'F10' }, // [USB: 0x43]
    0x7A: { code: 'F11' }, // [USB: 0x44]
    0x7B: { code: 'F12' }, // [USB: 0x45]
    0x7C: { code: 'F13' }, // [USB: 0x68]
    0x7D: { code: 'F14' }, // [USB: 0x69]
    0x7E: { code: 'F15' }, // [USB: 0x6a]
    0x7F: { code: 'F16' }, // [USB: 0x6b]

    0x80: { code: 'F17' }, // [USB: 0x6c]
    0x81: { code: 'F18' }, // [USB: 0x6d]
    0x82: { code: 'F19' }, // [USB: 0x6e]
    0x83: { code: 'F20' }, // [USB: 0x6f]
    0x84: { code: 'F21' }, // [USB: 0x70]
    0x85: { code: 'F22' }, // [USB: 0x71]
    0x86: { code: 'F23' }, // [USB: 0x72]
    0x87: { code: 'F24' }, // [USB: 0x73]
    // 0x88-0x8F - unassigned

    0x90: { code: 'NumLock', location: NUMPAD }, // [USB: 0x53]
    0x91: { code: 'ScrollLock' }, // [USB: 0x47]
    // 0x92-0x96 - OEM specific
    // 0x97-0x9F - unassigned

    // NOTE: 0xA0-0xA5 usually mapped to 0x10-0x12 in browsers
    0xA0: { code: 'ShiftLeft', location: LEFT }, // [USB: 0xe1]
    0xA1: { code: 'ShiftRight', location: RIGHT }, // [USB: 0xe5]
    0xA2: { code: 'ControlLeft', location: LEFT }, // [USB: 0xe0]
    0xA3: { code: 'ControlRight', location: RIGHT }, // [USB: 0xe4]
    0xA4: { code: 'AltLeft', location: LEFT }, // [USB: 0xe2]
    0xA5: { code: 'AltRight', location: RIGHT }, // [USB: 0xe6]

    0xA6: { code: 'BrowserBack' }, // [USB: 0x0c/0x0224]
    0xA7: { code: 'BrowserForward' }, // [USB: 0x0c/0x0225]
    0xA8: { code: 'BrowserRefresh' }, // [USB: 0x0c/0x0227]
    0xA9: { code: 'BrowserStop' }, // [USB: 0x0c/0x0226]
    0xAA: { code: 'BrowserSearch' }, // [USB: 0x0c/0x0221]
    0xAB: { code: 'BrowserFavorites' }, // [USB: 0x0c/0x0228]
    0xAC: { code: 'BrowserHome' }, // [USB: 0x0c/0x0222]
    0xAD: { code: 'AudioVolumeMute' }, // [USB: 0x7f]
    0xAE: { code: 'AudioVolumeDown' }, // [USB: 0x81]
    0xAF: { code: 'AudioVolumeUp' }, // [USB: 0x80]

    0xB0: { code: 'MediaTrackNext' }, // [USB: 0x0c/0x00b5]
    0xB1: { code: 'MediaTrackPrevious' }, // [USB: 0x0c/0x00b6]
    0xB2: { code: 'MediaStop' }, // [USB: 0x0c/0x00b7]
    0xB3: { code: 'MediaPlayPause' }, // [USB: 0x0c/0x00cd]
    0xB4: { code: 'LaunchMail' }, // [USB: 0x0c/0x018a]
    0xB5: { code: 'MediaSelect' },
    0xB6: { code: 'LaunchApp1' },
    0xB7: { code: 'LaunchApp2' },
    // 0xB8-0xB9 - reserved
    0xBA: { code: 'Semicolon',  keyCap: ';' }, // [USB: 0x33] ;: (US Standard 101)
    0xBB: { code: 'Equal', keyCap: '=' }, // [USB: 0x2e] =+
    0xBC: { code: 'Comma', keyCap: ',' }, // [USB: 0x36] ,<
    0xBD: { code: 'Minus', keyCap: '-' }, // [USB: 0x2d] -_
    0xBE: { code: 'Period', keyCap: '.' }, // [USB: 0x37] .>
    0xBF: { code: 'Slash', keyCap: '/' }, // [USB: 0x38] /? (US Standard 101)

    0xC0: { code: 'Backquote', keyCap: '`' }, // [USB: 0x35] `~ (US Standard 101)
    // 0xC1-0xCF - reserved

    // 0xD0-0xD7 - reserved
    // 0xD8-0xDA - unassigned
    0xDB: { code: 'BracketLeft', keyCap: '[' }, // [USB: 0x2f] [{ (US Standard 101)
    0xDC: { code: 'Backslash',  keyCap: '\\' }, // [USB: 0x31] \| (US Standard 101)
    0xDD: { code: 'BracketRight', keyCap: ']' }, // [USB: 0x30] ]} (US Standard 101)
    0xDE: { code: 'Quote', keyCap: '\'' }, // [USB: 0x34] '" (US Standard 101)
    // 0xDF - miscellaneous/varies

    // 0xE0 - reserved
    // 0xE1 - OEM specific
    0xE2: { code: 'IntlBackslash',  keyCap: '\\' }, // [USB: 0x64] \| (UK Standard 102)
    // 0xE3-0xE4 - OEM specific
    0xE5: { code: 'Process' }, // (Not in D3E)
    // 0xE6 - OEM specific
    // 0xE7 - VK_PACKET
    // 0xE8 - unassigned
    // 0xE9-0xEF - OEM specific

    // 0xF0-0xF5 - OEM specific
    0xF6: { code: 'Attn' }, // [USB: 0x9a] (Not in D3E)
    0xF7: { code: 'CrSel' }, // [USB: 0xa3] (Not in D3E)
    0xF8: { code: 'ExSel' }, // [USB: 0xa4] (Not in D3E)
    0xF9: { code: 'EraseEof' }, // (Not in D3E)
    0xFA: { code: 'Play' }, // (Not in D3E)
    0xFB: { code: 'ZoomToggle' }, // (Not in D3E)
    // 0xFC - VK_NONAME - reserved
    // 0xFD - VK_PA1
    0xFE: { code: 'Clear' } // [USB: 0x9c] (Not in D3E)
  };

  // No legacy keyCode, but listed in D3E:

  // code: usb
  // 'IntlHash': 0x070032,
  // 'IntlRo': 0x070087,
  // 'IntlYen': 0x070089,
  // 'NumpadBackspace': 0x0700bb,
  // 'NumpadClear': 0x0700d8,
  // 'NumpadClearEntry': 0x0700d9,
  // 'NumpadMemoryAdd': 0x0700d3,
  // 'NumpadMemoryClear': 0x0700d2,
  // 'NumpadMemoryRecall': 0x0700d1,
  // 'NumpadMemoryStore': 0x0700d0,
  // 'NumpadMemorySubtract': 0x0700d4,
  // 'NumpadParenLeft': 0x0700b6,
  // 'NumpadParenRight': 0x0700b7,

  //--------------------------------------------------------------------
  //
  // Browser/OS Specific Mappings
  //
  //--------------------------------------------------------------------

  mergeIf(keyCodeToInfoTable,
          'moz', {
            0x3B: { code: 'Semicolon', keyCap: ';' }, // [USB: 0x33] ;: (US Standard 101)
            0x3D: { code: 'Equal', keyCap: '=' }, // [USB: 0x2e] =+
            0x6B: { code: 'Equal', keyCap: '=' }, // [USB: 0x2e] =+
            0x6D: { code: 'Minus', keyCap: '-' }, // [USB: 0x2d] -_
            0xBB: { code: 'NumpadAdd', keyCap: '+', location: NUMPAD }, // [USB: 0x57]
            0xBD: { code: 'NumpadSubtract', keyCap: '-', location: NUMPAD } // [USB: 0x56]
          });

  mergeIf(keyCodeToInfoTable,
          'moz-mac', {
            0x0C: { code: 'NumLock', location: NUMPAD }, // [USB: 0x53]
            0xAD: { code: 'Minus', keyCap: '-' } // [USB: 0x2d] -_
          });

  mergeIf(keyCodeToInfoTable,
          'moz-win', {
            0xAD: { code: 'Minus', keyCap: '-' } // [USB: 0x2d] -_
          });

  mergeIf(keyCodeToInfoTable,
          'chrome-mac', {
            0x5D: { code: 'MetaRight', location: RIGHT } // [USB: 0xe7]
          });

  // Windows via Bootcamp (!)
  if (0) {
    mergeIf(keyCodeToInfoTable,
            'chrome-win', {
              0xC0: { code: 'Quote', keyCap: '\'' }, // [USB: 0x34] '" (US Standard 101)
              0xDE: { code: 'Backslash',  keyCap: '\\' }, // [USB: 0x31] \| (US Standard 101)
              0xDF: { code: 'Backquote', keyCap: '`' } // [USB: 0x35] `~ (US Standard 101)
            });

    mergeIf(keyCodeToInfoTable,
            'ie', {
              0xC0: { code: 'Quote', keyCap: '\'' }, // [USB: 0x34] '" (US Standard 101)
              0xDE: { code: 'Backslash',  keyCap: '\\' }, // [USB: 0x31] \| (US Standard 101)
              0xDF: { code: 'Backquote', keyCap: '`' } // [USB: 0x35] `~ (US Standard 101)
            });
  }

  mergeIf(keyCodeToInfoTable,
          'safari', {
            0x03: { code: 'Enter' }, // [USB: 0x28] old Safari
            0x19: { code: 'Tab' } // [USB: 0x2b] old Safari for Shift+Tab
          });

  mergeIf(keyCodeToInfoTable,
          'ios', {
            0x0A: { code: 'Enter', location: STANDARD } // [USB: 0x28]
          });

  mergeIf(keyCodeToInfoTable,
          'safari-mac', {
            0x5B: { code: 'MetaLeft', location: LEFT }, // [USB: 0xe3]
            0x5D: { code: 'MetaRight', location: RIGHT }, // [USB: 0xe7]
            0xE5: { code: 'KeyQ', keyCap: 'Q' } // [USB: 0x14] On alternate presses, Ctrl+Q sends this
          });

  //--------------------------------------------------------------------
  //
  // Identifier Mappings
  //
  //--------------------------------------------------------------------

  // Cases where newer-ish browsers send keyIdentifier which can be
  // used to disambiguate keys.

  // keyIdentifierTable[keyIdentifier] -> keyInfo

  var keyIdentifierTable = {};
  if ('cros' === os) {
    keyIdentifierTable['U+00A0'] = { code: 'ShiftLeft', location: LEFT };
    keyIdentifierTable['U+00A1'] = { code: 'ShiftRight', location: RIGHT };
    keyIdentifierTable['U+00A2'] = { code: 'ControlLeft', location: LEFT };
    keyIdentifierTable['U+00A3'] = { code: 'ControlRight', location: RIGHT };
    keyIdentifierTable['U+00A4'] = { code: 'AltLeft', location: LEFT };
    keyIdentifierTable['U+00A5'] = { code: 'AltRight', location: RIGHT };
  }
  if ('chrome-mac' === browser_os) {
    keyIdentifierTable['U+0010'] = { code: 'ContextMenu' };
  }
  if ('safari-mac' === browser_os) {
    keyIdentifierTable['U+0010'] = { code: 'ContextMenu' };
  }
  if ('ios' === os) {
    // These only generate keyup events
    keyIdentifierTable['U+0010'] = { code: 'Function' };

    keyIdentifierTable['U+001C'] = { code: 'ArrowLeft' };
    keyIdentifierTable['U+001D'] = { code: 'ArrowRight' };
    keyIdentifierTable['U+001E'] = { code: 'ArrowUp' };
    keyIdentifierTable['U+001F'] = { code: 'ArrowDown' };

    keyIdentifierTable['U+0001'] = { code: 'Home' }; // [USB: 0x4a] Fn + ArrowLeft
    keyIdentifierTable['U+0004'] = { code: 'End' }; // [USB: 0x4d] Fn + ArrowRight
    keyIdentifierTable['U+000B'] = { code: 'PageUp' }; // [USB: 0x4b] Fn + ArrowUp
    keyIdentifierTable['U+000C'] = { code: 'PageDown' }; // [USB: 0x4e] Fn + ArrowDown
  }

  //--------------------------------------------------------------------
  //
  // Location Mappings
  //
  //--------------------------------------------------------------------

  // Cases where newer-ish browsers send location/keyLocation which
  // can be used to disambiguate keys.

  // locationTable[location][keyCode] -> keyInfo
  var locationTable = [];
  locationTable[LEFT] = {
    0x10: { code: 'ShiftLeft', location: LEFT }, // [USB: 0xe1]
    0x11: { code: 'ControlLeft', location: LEFT }, // [USB: 0xe0]
    0x12: { code: 'AltLeft', location: LEFT } // [USB: 0xe2]
  };
  locationTable[RIGHT] = {
    0x10: { code: 'ShiftRight', location: RIGHT }, // [USB: 0xe5]
    0x11: { code: 'ControlRight', location: RIGHT }, // [USB: 0xe4]
    0x12: { code: 'AltRight', location: RIGHT } // [USB: 0xe6]
  };
  locationTable[NUMPAD] = {
    0x0D: { code: 'NumpadEnter', location: NUMPAD } // [USB: 0x58]
  };

  mergeIf(locationTable[NUMPAD], 'moz', {
    0x6D: { code: 'NumpadSubtract', location: NUMPAD }, // [USB: 0x56]
    0x6B: { code: 'NumpadAdd', location: NUMPAD } // [USB: 0x57]
  });
  mergeIf(locationTable[LEFT], 'moz-mac', {
    0xE0: { code: 'MetaLeft', location: LEFT } // [USB: 0xe3]
  });
  mergeIf(locationTable[RIGHT], 'moz-mac', {
    0xE0: { code: 'MetaRight', location: RIGHT } // [USB: 0xe7]
  });
  mergeIf(locationTable[RIGHT], 'moz-win', {
    0x5B: { code: 'MetaRight', location: RIGHT } // [USB: 0xe7]
  });


  mergeIf(locationTable[RIGHT], 'mac', {
    0x5D: { code: 'MetaRight', location: RIGHT } // [USB: 0xe7]
  });

  mergeIf(locationTable[NUMPAD], 'chrome-mac', {
    0x0C: { code: 'NumLock', location: NUMPAD } // [USB: 0x53]
  });

  mergeIf(locationTable[NUMPAD], 'safari-mac', {
    0x0C: { code: 'NumLock', location: NUMPAD }, // [USB: 0x53]
    0xBB: { code: 'NumpadAdd', location: NUMPAD }, // [USB: 0x57]
    0xBD: { code: 'NumpadSubtract', location: NUMPAD }, // [USB: 0x56]
    0xBE: { code: 'NumpadDecimal', location: NUMPAD }, // [USB: 0x63]
    0xBF: { code: 'NumpadDivide', location: NUMPAD } // [USB: 0x54]
  });


  //--------------------------------------------------------------------
  //
  // Key Values
  //
  //--------------------------------------------------------------------

  // Mapping from `code` values to `key` values. Values defined at:
  // https://w3c.github.io/uievents-key/
  // Entries are only provided when `key` differs from `code`. If
  // printable, `shiftKey` has the shifted printable character. This
  // assumes US Standard 101 layout

  var codeToKeyTable = {
    // Modifier Keys
    ShiftLeft: { key: 'Shift' },
    ShiftRight: { key: 'Shift' },
    ControlLeft: { key: 'Control' },
    ControlRight: { key: 'Control' },
    AltLeft: { key: 'Alt' },
    AltRight: { key: 'Alt' },
    MetaLeft: { key: 'Meta' },
    MetaRight: { key: 'Meta' },

    // Whitespace Keys
    NumpadEnter: { key: 'Enter' },
    Space: { key: ' ' },

    // Printable Keys
    Digit0: { key: '0', shiftKey: ')' },
    Digit1: { key: '1', shiftKey: '!' },
    Digit2: { key: '2', shiftKey: '@' },
    Digit3: { key: '3', shiftKey: '#' },
    Digit4: { key: '4', shiftKey: '$' },
    Digit5: { key: '5', shiftKey: '%' },
    Digit6: { key: '6', shiftKey: '^' },
    Digit7: { key: '7', shiftKey: '&' },
    Digit8: { key: '8', shiftKey: '*' },
    Digit9: { key: '9', shiftKey: '(' },
    KeyA: { key: 'a', shiftKey: 'A' },
    KeyB: { key: 'b', shiftKey: 'B' },
    KeyC: { key: 'c', shiftKey: 'C' },
    KeyD: { key: 'd', shiftKey: 'D' },
    KeyE: { key: 'e', shiftKey: 'E' },
    KeyF: { key: 'f', shiftKey: 'F' },
    KeyG: { key: 'g', shiftKey: 'G' },
    KeyH: { key: 'h', shiftKey: 'H' },
    KeyI: { key: 'i', shiftKey: 'I' },
    KeyJ: { key: 'j', shiftKey: 'J' },
    KeyK: { key: 'k', shiftKey: 'K' },
    KeyL: { key: 'l', shiftKey: 'L' },
    KeyM: { key: 'm', shiftKey: 'M' },
    KeyN: { key: 'n', shiftKey: 'N' },
    KeyO: { key: 'o', shiftKey: 'O' },
    KeyP: { key: 'p', shiftKey: 'P' },
    KeyQ: { key: 'q', shiftKey: 'Q' },
    KeyR: { key: 'r', shiftKey: 'R' },
    KeyS: { key: 's', shiftKey: 'S' },
    KeyT: { key: 't', shiftKey: 'T' },
    KeyU: { key: 'u', shiftKey: 'U' },
    KeyV: { key: 'v', shiftKey: 'V' },
    KeyW: { key: 'w', shiftKey: 'W' },
    KeyX: { key: 'x', shiftKey: 'X' },
    KeyY: { key: 'y', shiftKey: 'Y' },
    KeyZ: { key: 'z', shiftKey: 'Z' },
    Numpad0: { key: '0' },
    Numpad1: { key: '1' },
    Numpad2: { key: '2' },
    Numpad3: { key: '3' },
    Numpad4: { key: '4' },
    Numpad5: { key: '5' },
    Numpad6: { key: '6' },
    Numpad7: { key: '7' },
    Numpad8: { key: '8' },
    Numpad9: { key: '9' },
    NumpadMultiply: { key: '*' },
    NumpadAdd: { key: '+' },
    NumpadComma: { key: ',' },
    NumpadSubtract: { key: '-' },
    NumpadDecimal: { key: '.' },
    NumpadDivide: { key: '/' },
    Semicolon: { key: ';', shiftKey: ':' },
    Equal: { key: '=', shiftKey: '+' },
    Comma: { key: ',', shiftKey: '<' },
    Minus: { key: '-', shiftKey: '_' },
    Period: { key: '.', shiftKey: '>' },
    Slash: { key: '/', shiftKey: '?' },
    Backquote: { key: '`', shiftKey: '~' },
    BracketLeft: { key: '[', shiftKey: '{' },
    Backslash: { key: '\\', shiftKey: '|' },
    BracketRight: { key: ']', shiftKey: '}' },
    Quote: { key: '\'', shiftKey: '"' },
    IntlBackslash: { key: '\\', shiftKey: '|' }
  };

  mergeIf(codeToKeyTable, 'mac', {
    MetaLeft: { key: 'Meta' },
    MetaRight: { key: 'Meta' }
  });

  // Corrections for 'key' names in older browsers (e.g. FF36-, IE9, etc)
  // https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent.key#Key_values
  var keyFixTable = {
    Add: '+',
    Decimal: '.',
    Divide: '/',
    Subtract: '-',
    Multiply: '*',
    Spacebar: ' ',
    Esc: 'Escape',
    Nonconvert: 'NonConvert',
    Left: 'ArrowLeft',
    Up: 'ArrowUp',
    Right: 'ArrowRight',
    Down: 'ArrowDown',
    Del: 'Delete',
    Menu: 'ContextMenu',
    MediaNextTrack: 'MediaTrackNext',
    MediaPreviousTrack: 'MediaTrackPrevious',
    SelectMedia: 'MediaSelect',
    HalfWidth: 'Hankaku',
    FullWidth: 'Zenkaku',
    RomanCharacters: 'Romaji',
    Crsel: 'CrSel',
    Exsel: 'ExSel',
    Zoom: 'ZoomToggle'
  };

  //--------------------------------------------------------------------
  //
  // Exported Functions
  //
  //--------------------------------------------------------------------


  var codeTable = remap(keyCodeToInfoTable, 'code');

  try {
    var nativeLocation = nativeKeyboardEvent && ('location' in new KeyboardEvent(''));
  } catch (_) {}

  function keyInfoForEvent(event) {
    var keyCode = 'keyCode' in event ? event.keyCode : 'which' in event ? event.which : 0;
    var keyInfo = (function(){
      if (nativeLocation || 'keyLocation' in event) {
        var location = nativeLocation ? event.location : event.keyLocation;
        if (location && keyCode in locationTable[location]) {
          return locationTable[location][keyCode];
        }
      }
      if ('keyIdentifier' in event && event.keyIdentifier in keyIdentifierTable) {
        return keyIdentifierTable[event.keyIdentifier];
      }
      if (keyCode in keyCodeToInfoTable) {
        return keyCodeToInfoTable[keyCode];
      }
      return null;
    }());

    // TODO: Track these down and move to general tables
    if (0) {
      // TODO: Map these for newerish browsers?
      // TODO: iOS only?
      // TODO: Override with more common keyIdentifier name?
      switch (event.keyIdentifier) {
      case 'U+0010': keyInfo = { code: 'Function' }; break;
      case 'U+001C': keyInfo = { code: 'ArrowLeft' }; break;
      case 'U+001D': keyInfo = { code: 'ArrowRight' }; break;
      case 'U+001E': keyInfo = { code: 'ArrowUp' }; break;
      case 'U+001F': keyInfo = { code: 'ArrowDown' }; break;
      }
    }

    if (!keyInfo)
      return null;

    var key = (function() {
      var entry = codeToKeyTable[keyInfo.code];
      if (!entry) return keyInfo.code;
      return (event.shiftKey && 'shiftKey' in entry) ? entry.shiftKey : entry.key;
    }());

    return {
      code: keyInfo.code,
      key: key,
      location: keyInfo.location,
      keyCap: keyInfo.keyCap
    };
  }

  function queryKeyCap(code, locale) {
    code = String(code);
    if (!codeTable.hasOwnProperty(code)) return 'Undefined';
    if (locale && String(locale).toLowerCase() !== 'en-us') throw Error('Unsupported locale');
    var keyInfo = codeTable[code];
    return keyInfo.keyCap || keyInfo.code || 'Undefined';
  }

  if ('KeyboardEvent' in global && 'defineProperty' in Object) {
    (function() {
      function define(o, p, v) {
        if (p in o) return;
        Object.defineProperty(o, p, v);
      }

      define(KeyboardEvent.prototype, 'code', { get: function() {
        var keyInfo = keyInfoForEvent(this);
        return keyInfo ? keyInfo.code : '';
      }});

      // Fix for nonstandard `key` values (FF36-)
      if ('key' in KeyboardEvent.prototype) {
        var desc = Object.getOwnPropertyDescriptor(KeyboardEvent.prototype, 'key');
        Object.defineProperty(KeyboardEvent.prototype, 'key', { get: function() {
          var key = desc.get.call(this);
          return keyFixTable.hasOwnProperty(key) ? keyFixTable[key] : key;
        }});
      }

      define(KeyboardEvent.prototype, 'key', { get: function() {
        var keyInfo = keyInfoForEvent(this);
        return (keyInfo && 'key' in keyInfo) ? keyInfo.key : 'Unidentified';
      }});

      define(KeyboardEvent.prototype, 'location', { get: function() {
        var keyInfo = keyInfoForEvent(this);
        return (keyInfo && 'location' in keyInfo) ? keyInfo.location : STANDARD;
      }});

      define(KeyboardEvent.prototype, 'locale', { get: function() {
        return '';
      }});
    }());
  }

  if (!('queryKeyCap' in global.KeyboardEvent))
    global.KeyboardEvent.queryKeyCap = queryKeyCap;

  // Helper for IE8-
  global.identifyKey = function(event) {
    if ('code' in event)
      return;

    var keyInfo = keyInfoForEvent(event);
    event.code = keyInfo ? keyInfo.code : '';
    event.key = (keyInfo && 'key' in keyInfo) ? keyInfo.key : 'Unidentified';
    event.location = ('location' in event) ? event.location :
      ('keyLocation' in event) ? event.keyLocation :
      (keyInfo && 'location' in keyInfo) ? keyInfo.location : STANDARD;
    event.locale = '';
  };

}(self));