initFadeOut() {
    this.el.className += ` ${this.fadeOutClass}`;
    if (this.cursor) this.cursor.className += ` ${this.fadeOutClass}`;
    return setTimeout(() => {
      this.arrayPos++;
      this.replaceText('');

      // Resets current string if end of loop reached
      if (this.strings.length > this.arrayPos) {
        this.typewrite(this.strings[this.sequence[this.arrayPos]], 0);
      } else {
        this.typewrite(this.strings[0], 0);
        this.arrayPos = 0;
      }
    }, this.fadeOutDelay);
  }
Adds a CSS class to fade out current string
@private