许多答案调用Math.random()的次数比必需的要多。或者他们希望这个数字的十六进制表示，有六个字符。

首先将随机浮点数乘以范围[0,0xffffff + 1)。现在我们的数字有了0xRRRRRR的形式和一些变化，这是一个有24位有效位的数字。一次读取4位，并使用该随机数[0,15]并在查找时将其转换为匹配的十六进制字符。

function randomColor() {
    var lookup = "0123456789abcdef";
    var seed = Math.random() * 0x1000000;
    return (
        "#" +
        lookup[(seed & 0xf00000) >> 20] +
        lookup[(seed & 0x0f0000) >> 16] +
        lookup[(seed & 0x00f000) >> 12] +
        lookup[(seed & 0x000f00) >> 8] +
        lookup[(seed & 0x0000f0) >> 4] +
        lookup[seed & 0x00000f]
    );
};

function randomColor(format = 'hex') {
    const rnd = Math.random().toString(16).slice(-6);
    if (format === 'hex') {
        return '#' + rnd;
    }
    if (format === 'rgb') {
        const [r, g, b] = rnd.match(/.{2}/g).map(c=>parseInt(c, 16));
        return `rgb(${r}, ${g}, ${b})`;
    }
}

您可以使用colorchain.js生成具有不同色调的颜色序列。

这个函数在两个方面超越了其他答案:

它试图生成尽可能不同的颜色 20种颜色中哪一种与欧几里得距离最远 其他的都在HSV锥内。

它允许你限制色调， 饱和度，或值范围，但它仍然试图选择颜色作为 在这个范围内尽可能的不同。

它不是超级高效，但对于合理的值(谁甚至可以轻松地区分100种颜色?)够快了。

请参阅 JSFiddle

  /**
   * Generates a random palette of HSV colors.  Attempts to pick colors
   * that are as distinct as possible within the desired HSV range.
   *
   * @param {number}    [options.numColors=10] - the number of colors to generate
   * @param {number[]}  [options.hRange=[0,1]] - the maximum range for generated hue
   * @param {number[]}  [options.sRange=[0,1]] - the maximum range for generated saturation
   * @param {number[]}  [options.vRange=[0,1]] - the maximum range for generated value
   * @param {number[][]}[options.exclude=[[0,0,0],[0,0,1]]] - colors to exclude
   *
   * @returns {number[][]} an array of HSV colors (each HSV color
   * is a [hue, saturation, value] array)
   */
  function randomHSVPalette(options) {
    function random(min, max) {
      return min + Math.random() * (max - min);
    }

    function HSVtoXYZ(hsv) {
      var h = hsv[0];
      var s = hsv[1];
      var v = hsv[2];
      var angle = h * Math.PI * 2;
      return [Math.sin(angle) * s * v,
              Math.cos(angle) * s * v,
              v];
    }

    function distSq(a, b) {
      var dx = a[0] - b[0];
      var dy = a[1] - b[1];
      var dz = a[2] - b[2];
      return dx * dx + dy * dy + dz * dz;
    }

    if (!options) {
      options = {};
    }

    var numColors = options.numColors || 10;
    var hRange = options.hRange || [0, 1];
    var sRange = options.sRange || [0, 1];
    var vRange = options.vRange || [0, 1];
    var exclude = options.exclude || [[0, 0, 0], [0, 0, 1]];

    var points = exclude.map(HSVtoXYZ);
    var result = [];

    while (result.length < numColors) {
      var bestHSV;
      var bestXYZ;
      var bestDist = 0;
      for (var i = 0; i < 20; i++) {
        var hsv = [random(hRange[0], hRange[1]), random(sRange[0], sRange[1]), random(vRange[0], vRange[1])];
        var xyz = HSVtoXYZ(hsv);
        var minDist = 10;
        points.forEach(function(point) {
          minDist = Math.min(minDist, distSq(xyz, point));
        });
        if (minDist > bestDist) {
          bestHSV = hsv;
          bestXYZ = xyz;
          bestDist = minDist;
        }
      }
      points.push(bestXYZ);
      result.push(bestHSV);
    }

    return result;
  }

  function HSVtoRGB(hsv) {
    var h = hsv[0];
    var s = hsv[1];
    var v = hsv[2];

    var i = ~~(h * 6);
    var f = h * 6 - i;
    var p = v * (1 - s);
    var q = v * (1 - f * s);
    var t = v * (1 - (1 - f) * s);
    v = ~~(255 * v);
    p = ~~(255 * p);
    q = ~~(255 * q);
    t = ~~(255 * t);
    switch (i % 6) {
      case 0: return [v, t, p];
      case 1: return [q, v, p];
      case 2: return [p, v, t];
      case 3: return [p, q, v];
      case 4: return [t, p, v];
      case 5: return [v, p, q];
    }
  }

  function RGBtoCSS(rgb) {
    var r = rgb[0];
    var g = rgb[1];
    var b = rgb[2];
    var rgb = (r << 16) + (g << 8) + b;
    return '#' + ('000000' + rgb.toString(16)).slice(-6);
  }

Use:

function random_color(format)
{
    var rint = Math.round(0xffffff * Math.random());
    switch(format)
    {
        case 'hex':
            return ('#0' + rint.toString(16)).replace(/^#0([0-9a-f]{6})$/i, '#$1');
            break;

        case 'rgb':
            return 'rgb(' + (rint >> 16) + ',' + (rint >> 8 & 255) + ',' + (rint & 255) + ')';
            break;

        default:
            return rint;
            break;
    }
}

升级版:

function random_color( format ){
  var rint = Math.floor( 0x100000000 * Math.random());
  switch( format ){
    case 'hex':
      return '#' + ('00000'   + rint.toString(16)).slice(-6).toUpperCase();
    case 'hexa':
      return '#' + ('0000000' + rint.toString(16)).slice(-8).toUpperCase();
    case 'rgb':
      return 'rgb('  + (rint & 255) + ',' + (rint >> 8 & 255) + ',' + (rint >> 16 & 255) + ')';
    case 'rgba':
      return 'rgba(' + (rint & 255) + ',' + (rint >> 8 & 255) + ',' + (rint >> 16 & 255) + ',' + (rint >> 24 & 255)/255 + ')';
    default:
      return rint;
  }
}

只是因为我可以，我创建了一个不可读的片段，在最小和最大十六进制代码之间随机…:

function a(f, s){
    if(!s || !s.length > 1) return "";
    var c = Math.floor(Math.random()*(parseInt("0x" + s.substr(0,2))-parseInt("0x" +     f.substr(0,2))+1)+parseInt("0x" + f.substr(0,2))).toString(16);
    return  (Array(3 - c.length).join("0")) + c + a(f.substr(2,f.length),s.substr(2,s.length));
}

A ("990099"，"ff00ff")→可能随机化→b5009e

它是成对的，a("12"，"f2")→可能随机化→8f。 但它不会超过f2。

var color = "#" + a("11","22") + a("33","44") + a("55","66");

即:

var color = "#" + a("113355","224466")

但速度较慢。