How to lighten/darken
let color = new Color("hsl(20, 100%, 30%)");
// HSL lightness adjustment
let lighter = color.clone();
lighter.hsl.lightness *= 1.5;
lighter;
// LCH lightness adjustment
let lighter2 = color.clone();
lighter2.lch.lightness *= 1.5;
lighter2;
// Tint
color.mix(new Color("white"), .5, {space: "hsl"});
More HSL ugliness:
let color1 = new Color("hsl(60, 100%, 50%)");
let color2 = new Color("hsl(230, 100%, 50%)");
let lighter1 = color1.clone();
let lighter2 = color2.clone();
lighter1.hsl.lightness = 70;
lighter1;
lighter2.hsl.lightness = 70;
lighter2;
lighter1.deltaE(color1, "2000");
lighter2.deltaE(color2, "2000");