index.js

rgb.forEach((color, i) => {
  var slider = d3
    .sliderBottom()
    .min(0)
    .max(255)
    .step(1)
    .width(300)
    .ticks(0)
    .default(rgb[i])
    .displayValue(false)
    .fill(colors[i])
    .handle(
      d3
        .symbol()
        .type(d3.symbolCircle)
        .size(200)()
    )
    .on('onchange', num => {
      rgb[i] = num;
      blob.style.fill = `#${num2hex(rgb)}`;
    });
  gColorPicker
    .append('g')
    .attr('transform', `translate(30,${60 * i})`)
    .call(slider);
});