Simple Button Class for p5.js

Button.js

class Button {
  constructor(label, x, y, colorHex = '#FF0000') {
    this.label = label;
    this.x = x;
    this.y = y;
    this.colorHex = colorHex;
    
    this.labelSize = textWidth(label);
    
    this.spacing = 20;
    
    this.width = this.labelSize + this.spacing;
    this.height = 25;
    
    this.normalBg = color(colorHex);
    this.normalFg = this.contrastColor(this.normalBg);
    
    this.hoverBg = this.normalFg;
    this.hoverFg = this.normalBg;
    
    this.hover = false;
    this.clicked = false;
  }
  
  draw() {
    push();
      noStroke();
      fill(!this.hover ? this.normalBg : this.hoverBg);
      rect(this.x, this.y, this.width, this.height);
      fill(!this.hover ? this.normalFg : this.hoverFg);
      text(this.label, 
           this.x + this.spacing * 0.5, 
           this.y + 17);
    pop();
  }
  
  mousePressed(cb) {
    if (this.hover) {
      cb();
    }
  }
  
  mouseMoved() {
    this.hover = this.checkIfMouseIsOverButton();
  }
  
  checkIfMouseIsOverButton() {
    let x = mouseX;
    let y = mouseY;
    let result = false;
    if (x > this.x &&
        x < this.x + this.width &&
        y > this.y &&
        y < this.y + this.height) 
    {
      result = true;
    }
    return result;
  }
  
  contrastColor(theColor) {
    let r = red(theColor);
    let g = green(theColor);
    let b = blue(theColor);
    let luma = ((0.299 * r) + (0.587 * g) + (0.114 * b)) / 255;
    return luma < 0.5 ? color('#FFF') : color('#000');
  }
}