<main class='container'></main>
<button>Show More</button>

.box {
  width: 200px;
  height: 50px;
  display: inline-block;
  font-size: 24px;
  text-align: center;
  line-height: 50px;  
}

const CSS_COLOR_NAMES = ['#333', "AliceBlue","AntiqueWhite","Aqua","Aquamarine","Azure","Beige","Bisque","Black","BlanchedAlmond","Blue","BlueViolet","Brown","BurlyWood","CadetBlue","Chartreuse","Chocolate","Coral","CornflowerBlue","Cornsilk","Crimson","Cyan","DarkBlue","DarkCyan","DarkGoldenRod","DarkGray","DarkGrey","DarkGreen","DarkKhaki","DarkMagenta","DarkOliveGreen","Darkorange","DarkOrchid","DarkRed","DarkSalmon","DarkSeaGreen","DarkSlateBlue","DarkSlateGray","DarkSlateGrey","DarkTurquoise","DarkViolet","DeepPink","DeepSkyBlue","DimGray","DimGrey","DodgerBlue","FireBrick","FloralWhite","ForestGreen","Fuchsia","Gainsboro","GhostWhite","Gold","GoldenRod","Gray","Grey","Green","GreenYellow","HoneyDew","HotPink","IndianRed","Indigo","Ivory","Khaki","Lavender","LavenderBlush","LawnGreen","LemonChiffon","LightBlue","LightCoral","LightCyan","LightGoldenRodYellow","LightGray","LightGrey","LightGreen","LightPink","LightSalmon","LightSeaGreen","LightSkyBlue","LightSlateGray","LightSlateGrey","LightSteelBlue","LightYellow","Lime","LimeGreen","Linen","Magenta","Maroon","MediumAquaMarine","MediumBlue","MediumOrchid","MediumPurple","MediumSeaGreen","MediumSlateBlue","MediumSpringGreen","MediumTurquoise","MediumVioletRed","MidnightBlue","MintCream","MistyRose","Moccasin","NavajoWhite","Navy","OldLace","Olive","OliveDrab","Orange","OrangeRed","Orchid","PaleGoldenRod","PaleGreen","PaleTurquoise","PaleVioletRed","PapayaWhip","PeachPuff","Peru","Pink","Plum","PowderBlue","Purple","Red","RosyBrown","RoyalBlue","SaddleBrown","Salmon","SandyBrown","SeaGreen","SeaShell","Sienna","Silver","SkyBlue","SlateBlue","SlateGray","SlateGrey","Snow","SpringGreen","SteelBlue","Tan","Teal","Thistle","Tomato","Turquoise","Violet","Wheat","White","WhiteSmoke","Yellow","YellowGreen"];

function getForegroundColor1(color) {
  return tinycolor(color).isDark() ? 'white' : 'black';
}

function getForegroundColor2(color) {
  const t = tinycolor(color);
  if (t.isDark()) {
    return t.complement().lighten(60).toHexString();
  } else {
    return t.complement().darken(60).toHexString();
  }
}

function invertColor(hexTripletColor) {
    var color = hexTripletColor;
    color = color.substring(1);           // remove #
    color = parseInt(color, 16);          // convert to integer
    color = 0xFFFFFF ^ color;             // invert three bytes
    color = color.toString(16);           // convert to hex
    color = ("000000" + color).slice(-6); // pad with leading zeros
    color = "#" + color;                  // prepend #
    return color;
}

function showMore() {
  const colors = _.sample(CSS_COLOR_NAMES, 10);
  const container = document.querySelector('.container');
  container.innerHTML = '';
  
  for (c of colors) {
    const el = document.createElement('div');
    el.classList.add('box');
    el.style.backgroundColor = c;

    container.appendChild(el);  
    el.style.color = getForegroundColor2(c);
    el.textContent = c;
  }  
}

document.querySelector('button').addEventListener('click', showMore);
showMore();