Unicoding emoji

gistfile1.txt

// see: https://medium.com/reactnative/emojis-in-javascript-f693d0eb79fb
// http://www.2ality.com/2013/09/javascript-unicode.html
function toUTF16(codePoint) {
  var TEN_BITS = parseInt('1111111111', 2);
  function u(codeUnit) {
    return '\\u'+codeUnit.toString(16).toUpperCase();
  }

  if (codePoint <= 0xFFFF) {
    return u(codePoint);
  }
  codePoint -= 0x10000;

  // Shift right to get to most significant 10 bits
  var leadSurrogate = 0xD800 + (codePoint >> 10);

  // Mask to get least significant 10 bits
  var tailSurrogate = 0xDC00 + (codePoint & TEN_BITS);

  return u(leadSurrogate) + u(tailSurrogate);
}

// using codePointAt, it's easy to go from emoji
// to decimal and back.
// Emoji to decimal representation
"😀".codePointAt(0)
>128512

// Decimal to emoji
String.fromCodePoint(128512)
>"😀"

// going from emoji to hexadecimal is a little
// bit trickier. To convert from decimal to hexadecimal,
// we can use toUTF16.
// Decimal to hexadecimal
toUTF16(128512)
> "\uD83D\uDE00"

// Hexadecimal to emoji
"\uD83D\uDE00"
> "😀"