長年の経験を持つ塗装職人が施工を担当

viewport

class ParallaxEffectBackground {
  constructor() {
    this.devided = 1.2;
    this.target = '.container-bg';
    this.setBackgroundPosition();
  }

  getScrollTop() {
    return Math.max(
      window.pageYOffset,
      document.documentElement.scrollTop,
      document.body.scrollTop,
      window.scrollY
    );
  }

  setBackgroundPosition() {
    document.addEventListener('scroll', e => {
      const scrollTop = this.getScrollTop();
      const position = scrollTop / this.devided;
      if (position) {
        document.querySelectorAll(this.target).forEach(element => {
          element.style.backgroundPosition = 'center calc(50% - ' + offset + 'px)';
        });
      }
    });
  }
}

document.addEventListener('DOMContentLoaded', event => {
  new ParallaxEffectBackground();
});