the-glorious-startpage/js/centered-box.js

class CenteredBox {
    constructor() {
        this._centeredBox = document.querySelector('#centeredBox');

        this._centeredBoxVisibility = true;

        this.showCenteredBox = this.showCenteredBox.bind(this);
        this.hideCenteredBox = this.hideCenteredBox.bind(this);
        this.toggleCenteredBox = this.toggleCenteredBox.bind(this);
    }

    showCenteredBox = () => {
        this._centeredBox.classList.remove('hiddenBox');
        this._centeredBoxVisibility = !this._centeredBoxVisibility;
    }

    hideCenteredBox = () => {
        this._centeredBox.classList.add('hiddenBox');
        this._centeredBoxVisibility = !this._centeredBoxVisibility;
    }

    toggleCenteredBox = () => {

        if (this._centeredBoxVisibility) {
            // hide centered box
            this.hideCenteredBox();      

        } else {
            // Show centered box
            this.showCenteredBox();
        }
    }
}