colors[rand()].user.js

// ==UserScript==
// @name         RohBot Color Randomizer
// @version      0.1
// @description  try to take over the world!
// @author       Rohansi
// @match        https://rohbot.net/
// @grant        GM_addStyle
// @require      https://raw.githubusercontent.com/garycourt/murmurhash-js/0197ce38bedac0e05f40b9d7152095d06db8292c/murmurhash3_gc.js
// ==/UserScript==

var seed = 7;
var cache = {};

function getColor(userId) {
    var hash = murmurhash3_32_gc(userId || "", seed);
    var colorName = "rand-" + hash;
    
    if (cache.hasOwnProperty(hash))
        return colorName;
    
    // get a positive value for the hue
    var deg = hash % 360;
    var h = deg < 0 ? 360 + deg : deg;
    
    // default L is 75
    var l = 75;
    
    // half of the hues are too light, for those we
    // decrease lightness
    if(h >= 30 && h <= 210) {
        l = 50;
    }
    
    // keep saturation above 50
    var s = 50 + Math.abs(hash) % 50;
    
    GM_addStyle(".styled-names ." + colorName + " { color: hsl(" + h + "," + s + "%," + l + "%); }");
    cache[hash] = true;
    return colorName;
}

chatMgr.lineFilter.add(function (line, prepend, e) {
    switch (line.Type) {
        case "chat":
            if (!line.SenderStyle) line.SenderStyle = getColor(line.SenderId);
            break;
        case "state":
            if (!line.ForStyle) line.ForStyle = getColor(line.ForId);
            if (!line.ByStyle && line.ById) line.ByStyle = getColor(line.ById);
            break
    }
});

chatMgr.userFilter.add(function (user, e) {
    if (!user.Style) user.Style = getColor(user.UserId);
});