callback for intersection observer

VisibleArea.js

intersectionCallback(entries, observer) {
    const self = this;
    entries.forEach(entry => {
      if(entry.isIntersecting) {
        // append the current row in visible area
        const divToAppendReactElement = document.createElement('div');
        divToAppendReactElement.id = `dom${this.currentScrollPosition}`;
        const newElement = ReactDOM.render(self.configureInsertedElement(), divToAppendReactElement);
        const parentNode = entry.target.parentNode;
        const target = document.getElementById(`end-sentinel${this.currentScrollPosition}`);
        // append the element just before the sentinel
        parentNode.insertBefore(newElement, target);
        //unobserve the current seltinel
        observer.unobserve(entry.target);
        // set the new intersection observers
        console.log(this.currentScrollPosition);
        this.currentScrollPosition = this.currentScrollPosition + 1;
        target.id = `end-sentinel${this.currentScrollPosition}`;
        this.lazyLoadImageRow();
        
      }
    })
  }