Generate gradient color from an arbitrary number of colors

color-gradient.js

function colorGradient(colors, fadeFraction) {
    if (fadeFraction >= 1) {
        return colors[colors.length - 1]
    } else if (fadeFraction <= 0) {
        return colors[0]
    }

    let fade = fadeFraction * (colors.length - 1);
    let interval = Math.trunc(fade);
    fade = fade - interval
    color1 = colors[interval];
    color2 = colors[interval + 1]

    var diffRed = color2.red - color1.red;
    var diffGreen = color2.green - color1.green;
    var diffBlue = color2.blue - color1.blue;

    var gradient = {
      red: parseInt(Math.floor(color1.red + (diffRed * fade)), 10),
      green: parseInt(Math.floor(color1.green + (diffGreen * fade)), 10),
      blue: parseInt(Math.floor(color1.blue + (diffBlue * fade)), 10),
    };

    return 'rgb(' + gradient.red + ',' + gradient.green + ',' + gradient.blue + ')';
  }