calculates nearest web safe color

gistfile1.js

/*
* "THE BEER-WARE LICENSE" (Revision 42):
* <[email protected]> wrote this file. As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you think
* this stuff is worth it, you can buy me a beer in return
*/

var int    = parseInt,
    sub    = String.prototype.substr,
    colors = {
      '000000':16,  '00005f':17,  '000087':18,  '0000af':19,  '0000d7':20,
      '0000ff':21,  '005f00':22,  '005f5f':23,  '005f87':24,  '005faf':25,
      '005fd7':26,  '005fff':27,  '008700':28,  '00875f':29,  '008787':30,
      '0087af':31,  '0087d7':32,  '0087ff':33,  '00af00':34,  '00af5f':35,
      '00af87':36,  '00afaf':37,  '00afd7':38,  '00afff':39,  '00d700':40,
      '00d75f':41,  '00d787':42,  '00d7af':43,  '00d7d7':44,  '00d7ff':45,
      '00ff00':46,  '00ff5f':47,  '00ff87':48,  '00ffaf':49,  '00ffd7':50,
      '00ffff':51,  '5f0000':52,  '5f005f':53,  '5f0087':54,  '5f00af':55,
      '5f00d7':56,  '5f00ff':57,  '5f5f00':58,  '5f5f5f':59,  '5f5f87':60,
      '5f5faf':61,  '5f5fd7':62,  '5f5fff':63,  '5f8700':64,  '5f875f':65,
      '5f8787':66,  '5f87af':67,  '5f87d7':68,  '5f87ff':69,  '5faf00':70,
      '5faf5f':71,  '5faf87':72,  '5fafaf':73,  '5fafd7':74,  '5fafff':75,
      '5fd700':76,  '5fd75f':77,  '5fd787':78,  '5fd7af':79,  '5fd7d7':80,
      '5fd7ff':81,  '5fff00':82,  '5fff5f':83,  '5fff87':84,  '5fffaf':85,
      '5fffd7':86,  '5fffff':87,  '870000':88,  '87005f':89,  '870087':90,
      '8700af':91,  '8700d7':92,  '8700ff':93,  '875f00':94,  '875f5f':95,
      '875f87':96,  '875faf':97,  '875fd7':98,  '875fff':99,  '878700':100,
      '87875f':101, '878787':102, '8787af':103, '8787d7':104, '8787ff':105,
      '87af00':106, '87af5f':107, '87af87':108, '87afaf':109, '87afd7':110,
      '87afff':111, '87d700':112, '87d75f':113, '87d787':114, '87d7af':115,
      '87d7d7':116, '87d7ff':117, '87ff00':118, '87ff5f':119, '87ff87':120,
      '87ffaf':121, '87ffd7':122, '87ffff':123, 'af0000':124, 'af005f':125,
      'af0087':126, 'af00af':127, 'af00d7':128, 'af00ff':129, 'af5f00':130,
      'af5f5f':131, 'af5f87':132, 'af5faf':133, 'af5fd7':134, 'af5fff':135,
      'af8700':136, 'af875f':137, 'af8787':138, 'af87af':139, 'af87d7':140,
      'af87ff':141, 'afaf00':142, 'afaf5f':143, 'afaf87':144, 'afafaf':145,
      'afafd7':146, 'afafff':147, 'afd700':148, 'afd75f':149, 'afd787':150,
      'afd7af':151, 'afd7d7':152, 'afd7ff':153, 'afff00':154, 'afff5f':155,
      'afff87':156, 'afffaf':157, 'afffd7':158, 'afffff':159, 'd70000':160,
      'd7005f':161, 'd70087':162, 'd700af':163, 'd700d7':164, 'd700ff':165,
      'd75f00':166, 'd75f5f':167, 'd75f87':168, 'd75faf':169, 'd75fd7':170,
      'd75fff':171, 'd78700':172, 'd7875f':173, 'd78787':174, 'd787af':175,
      'd787d7':176, 'd787ff':177, 'd7af00':178, 'd7af5f':179, 'd7af87':180,
      'd7afaf':181, 'd7afd7':182, 'd7afff':183, 'd7d700':184, 'd7d75f':185,
      'd7d787':186, 'd7d7af':187, 'd7d7d7':188, 'd7d7ff':189, 'd7ff00':190,
      'd7ff5f':191, 'd7ff87':192, 'd7ffaf':193, 'd7ffd7':194, 'd7ffff':195,
      'ff0000':196, 'ff005f':197, 'ff0087':198, 'ff00af':199, 'ff00d7':200,
      'ff00ff':201, 'ff5f00':202, 'ff5f5f':203, 'ff5f87':204, 'ff5faf':205,
      'ff5fd7':206, 'ff5fff':207, 'ff8700':208, 'ff875f':209, 'ff8787':210,
      'ff87af':211, 'ff87d7':212, 'ff87ff':213, 'ffaf00':214, 'ffaf5f':215,
      'ffaf87':216, 'ffafaf':217, 'ffafd7':218, 'ffafff':219, 'ffd700':220,
      'ffd75f':221, 'ffd787':222, 'ffd7af':223, 'ffd7d7':224, 'ffd7ff':225,
      'ffff00':226, 'ffff5f':227, 'ffff87':228, 'ffffaf':229, 'ffffd7':230,
      'ffffff':231, '080808':232, '121212':233, '1c1c1c':234, '262626':235,
      '303030':236, '3a3a3a':237, '444444':238, '4e4e4e':239, '585858':240,
      '626262':241, '6c6c6c':242, '767676':243, '808080':244, '8a8a8a':245,
      '949494':246, '9e9e9e':247, 'a8a8a8':248, 'b2b2b2':249, 'bcbcbc':250,
      'c6c6c6':251, 'd0d0d0':252, 'dadada':253, 'e4e4e4':254, 'eeeeee':255
};

// calc color distance
function colorDistance(c1, c2) {

  var diffRed   = (int(sub.call(c1, 0, 2), 16) - int(sub.call(c2, 0, 2), 16)),
      diffGreen = (int(sub.call(c1, 2, 2), 16) - int(sub.call(c2, 2, 2), 16)),
      diffBlue  = (int(sub.call(c1, 4, 2), 16) - int(sub.call(c2, 4, 2), 16));

  return ((diffRed * diffRed) + (diffGreen * diffGreen) + (diffBlue * diffBlue));
};

// best match color
function bestMatch(hex, hexOnly) {
  var match    = null,
      nearest  = 0,
      distance = 0,
      key;

  for(key in colors) {
    distance = colorDistance(hex, key);
    if (distance < nearest || match == null) {
      match   = key;
      nearest = distance;
    };
  };

  return (hexOnly ? match : colors[match]);
};

// example

console.log("CCA781", bestMatch("CCA781", true), bestMatch("CCA781"));
console.log("CCBDAE", bestMatch("CCBDAE", true), bestMatch("CCBDAE"));
console.log("A281CC", bestMatch("A281CC", true), bestMatch("A281CC"));
console.log("76BA53", bestMatch("76BA53", true), bestMatch("76BA53"));