Lighten and Dark Color Generator

color.js

class Color {
  constructor (color) {
    this.color = color
  }

  _transform(color, percent) {
    var R = parseInt(color.substring(1,3),16);
    var G = parseInt(color.substring(3,5),16);
    var B = parseInt(color.substring(5,7),16);

    R = parseInt(R * (100 + percent) / 100);
    G = parseInt(G * (100 + percent) / 100);
    B = parseInt(B * (100 + percent) / 100);

    R = ((R<255)?R:255).toString(16);  
    G = ((G<255)?G:255).toString(16);  
    B = ((B<255)?B:255).toString(16);

    var RR = ((R.length==1)?"0"+R:R);
    var GG = ((G.length==1)?"0"+G:G);
    var BB = ((B.length==1)?"0"+B:B);

    return "#"+RR+GG+BB;
  }

  darken(percent) {
    return this._transform(this.color, -(percent))
  }
  lighten(percent) {
    return this._transform(this.color, percent)
  }

  darkenShade(level = 5) {
    return new Array(level).fill(null).map((val, index) => this.darken((index+1) * 10))
  }
  lightenShade(level = 5) {
    return new Array(level).fill(null).map((val, index) => this.lighten((index+1) * 10))
  }
}

module.exports = Color