Get text within rectangle

prototype.js

(() => {
  const MAX_BASENAME_LENGTH = 64;
  const clicks = [];
  const getNodesInRectangle = (topLeft, bottomRight) =>
    Array.from(document.querySelectorAll("*").values()).filter(node => {
      const { x, y, width, height } = node.getBoundingClientRect();
      return (
        x >= topLeft.x &&
        x + width <= bottomRight.x &&
        y >= topLeft.y &&
        y + height <= bottomRight.y
      );
    });
  const extractSelection = (topLeft, bottomRight) => {
    console.log({ topLeft, bottomRight });
    const nodes = getNodesInRectangle(topLeft, bottomRight);
    console.log({ nodes });
    return nodes.map(node => node.textContent).join(" ");
  };
  const saveToFile = text => {
    const href = `data:text/plain;base64,${btoa(text)}`;
    const { location} = document;
    const baseName = `${location.hostname}-${location.pathname}`.slice(0, MAX_BASENAME_LENGTH);
    const a = document.createElement("a");
    a.setAttribute(
      "href",
      href,
    );
    a.setAttribute(
      "download",
      `${baseName}.txt`,
    );
    a.style.display = "none";
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
  };
  const onClick = event => {
    const point = { x: event.clientX, y: event.clientY };
    console.log(point);
    clicks.push(point);
    if (clicks.length === 2) {
      document.removeEventListener("mousedown", onClick);
      const [topLeft, bottomRight] = clicks;
      saveToFile(extractSelection(topLeft, bottomRight));
    }
  };
  document.addEventListener("mousedown", onClick);
})();