getRandomColor

getRandomColor.js

if (typeof getRandomColor === "undefined") {
    var getRandomColor = function(type) {
        var _c;

        if (type)  type = type.toUpperCase();

        switch (type) {
        case "RGB":
            _c = "rgb(" + (Math.random() * 256 | 0) + ", " + (Math.random() * 256 | 0) + ", " + (Math.random() * 256 | 0) + ")";
            break;
        case "RGBA":
            _c = "rgba(" + (Math.random() * 256 | 0) + ", " + (Math.random() * 256 | 0) + ", " + (Math.random() * 256 | 0) + ", " + (Math.random() * 101 | 0) / 100 + ")";
            break;
        case "HSL":
            _c = "hsl(" + (Math.random() * 361 | 0) + ", " + (Math.random() * 101 | 0) + "%, " + (Math.random() * 101 | 0) + "%)";
            break;
        case "HSLA":
            _c = "hsla(" + (Math.random() * 361 | 0) + ", " + (Math.random() * 101 | 0) + "%, " + (Math.random() * 101 | 0) + "%, " + (Math.random() * 101 | 0) / 100 + ")";
            break;
        default:
            _c = "#" + ("000000" + (Math.random() * 0x1000000 | 0).toString(16)).substr(-6);
            break;
        }

        if (/^(MSF|AHEX)$/.test(type))  _c += ("00" + (Math.random() * 256 | 0).toString(16)).substr(-2);

        return _c;
    };
}

getRandomColor_test.js

var a = ["RGB", "RGBA", "HSL", "HSLA", "HEX", "MSF", "AHEX", ""];

for (var i = 0; i < a.length; i++) {
  document.write(a[i] + "<br>");

  for (var j = 0; j < 100; j++) {
    var color = getRandomColor(a[i]);
    document.write(color + "<br>");
  }

  document.write("<hr>");
}

memo.txt

※以下の２つは同じ
  if (type === "MSF" || type === "AHEX"){}
  if (/^(MSF|AHEX)$/.test(type)) {}

※参考 : https://github.com/shichuan/javascript-patterns/blob/master/general-patterns/conditionals.html