React: Get width, height, and coordinates of a react object

  componentDidMount() {
    var div = document.querySelector(".sliderWrapper");
    var divOffset = this.offset(div);
    console.log(divOffset.left, divOffset.top);

    var dropMen = this.refs.targetDiv;
    var specs = dropMen.getBoundingClientRect();
    console.log(specs);
  }

  offset(el) {
    var rect = el.getBoundingClientRect(),
      scrollLeft = window.pageXOffset || document.documentElement.scrollLeft,
      scrollTop = window.pageYOffset || document.documentElement.scrollTop;
    return { top: rect.top + scrollTop, left: rect.left + scrollLeft };
  }
  
  
  <div className="block-image" ref="targetDiv">