Highlight text on selection in React

Implement a hook in React that will return the selected text on the web page and the coordinates of the selection so that a popup can be shown to Tweet the selected text just like Medium.

To implement this we will listen to the mouseup event and on the event get the window selection to get the highlighted text and the current node of the text. The text can be overlapping thus we can get the start and the end node.

We can pass the element reference to the hook just to restrict the selection of particular elements. Check if the selected text’s start and end node is part of the element then only get the selection and its coordinates.

Store the value in a state and return the data.

const useSelectionText = (ref) => {
  // to store the selected text
  // and tools
  const [data, setData] = useState({ showTools: false });

  // handle the mouseup event
  const onMouseup = () => {

    // get the window selection
    const selection = window.getSelection();

    // get the parent node
    const startNode = selection.getRangeAt(0).startContainer.parentNode;

    // get the end node
    const endNode = selection.getRangeAt(0).endContainer.parentNode;

    // if the current element is is not part of the selection node
    // do not show tools
    if (!startNode.isSameNode(ref.current) || !startNode.isSameNode(endNode)) {
      setData({
        showTools: false,
      });
      return;
    }

    // get the coordinates of the selection
    const { x, y, width } = selection.getRangeAt(0).getBoundingClientRect();

    // if not much is selected
    // do not show tools
    if (!width) {
      setData({
        showTools: false,
      });
      return;
    }

    // if text is selected
    // update the selection
    // and the co-ordinates
    // the y position is adjusted to show bar above the selection
    if (selection.toString()) {
      setData({
        x: x,
        y: y + window.scrollY - 25,
        showTools: true,
        selectedText: selection.toString(),
        width,
      });
    }
  };

  // handle selection
  // on the mouseup event
  useEffect(() => {
    // add the event
    document.addEventListener("mouseup", onMouseup);

    // remove the listener
    return () => {
      document.removeEventListener("mouseup", onMouseup);
    };
  }, []);

  // return the data
  return data;
};

Usage

const Example = () => {
  const ref = useRef();
  const data = useSelectionText(ref);

  return (
    <div>
      {data.showTools && (
        // position the popover according to the need
        <span
          style={{
            position: "absolute",
            left: `${data.x + data.width / 4}px`,
            top: `${data.y}px`,
            width: data.width / 2,
            display: "inline-block",
            height: "20px",
            textAlign: "center",
          }}
        >
          {/* twitter icon */}
          <svg style={{ width: "24px", height: "24px" }} viewBox="0 0 24 24">
            <path
              fill="#000000"
              d="M22.46,6C21.69,6.35 20.86,6.58 20,6.69C20.88,6.16 21.56,5.32 21.88,4.31C21.05,4.81 20.13,5.16 19.16,5.36C18.37,4.5 17.26,4 16,4C13.65,4 11.73,5.92 11.73,8.29C11.73,8.63 11.77,8.96 11.84,9.27C8.28,9.09 5.11,7.38 3,4.79C2.63,5.42 2.42,6.16 2.42,6.94C2.42,8.43 3.17,9.75 4.33,10.5C3.62,10.5 2.96,10.3 2.38,10C2.38,10 2.38,10 2.38,10.03C2.38,12.11 3.86,13.85 5.82,14.24C5.46,14.34 5.08,14.39 4.69,14.39C4.42,14.39 4.15,14.36 3.89,14.31C4.43,16 6,17.26 7.89,17.29C6.43,18.45 4.58,19.13 2.56,19.13C2.22,19.13 1.88,19.11 1.54,19.07C3.44,20.29 5.7,21 8.12,21C16,21 20.33,14.46 20.33,8.79C20.33,8.6 20.33,8.42 20.32,8.23C21.16,7.63 21.88,6.87 22.46,6Z"
            />
          </svg>
          {/* edit icon */}
          <svg style={{ width: "24px", height: "24px" }} viewBox="0 0 24 24">
            <path
              fill="#000000"
              d="M18.5,1.15C17.97,1.15 17.46,1.34 17.07,1.73L11.26,7.55L16.91,13.2L22.73,7.39C23.5,6.61 23.5,5.35 22.73,4.56L19.89,1.73C19.5,1.34 19,1.15 18.5,1.15M10.3,8.5L4.34,14.46C3.56,15.24 3.56,16.5 4.36,17.31C3.14,18.54 1.9,19.77 0.67,21H6.33L7.19,20.14C7.97,20.9 9.22,20.89 10,20.12L15.95,14.16"
            />
          </svg>
        </span>
      )}
      <div ref={ref}>
        There are many variations of passages of Lorem Ipsum available, but the majority have
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        with a handful of model sentence structures, to generate Lorem Ipsum which looks reasonable.
        The generated Lorem Ipsum is therefore always free from repetition, injected humour, or
        non-characteristic words etc. Contrary to popular belief, Lorem Ipsum is not simply random
        text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000
        years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia,
        looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and
        going through the cites of the word in classical literature, discovered the undoubtable
        source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus Bonorum et
        Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a
        treatise on the theory of ethics, very popular during the Renaissance. The first line of
        Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in section 1.10.32.
      </div>
    </div>
  );
};

Output