@elv1n/react-use-measure/dist/web.js

measure view bounds

import { useState, useRef, useEffect, useMemo, useCallback } from 'react';
import { debounce } from 'debounce';

function useMeasure({
  debounce: debounce$1,
  scroll,
  polyfill
} = {
  debounce: 0,
  scroll: false
}) {
  const ResizeObserver = polyfill || (typeof window === 'undefined' ? class ResizeObserver {} : window.ResizeObserver);

  if (!ResizeObserver) {
    throw new Error('This browser does not support ResizeObserver out of the box. See: https://github.com/react-spring/react-use-measure/#resize-observer-polyfills');
  }

  const [bounds, set] = useState({
    left: 0,
    top: 0,
    width: 0,
    height: 0,
    bottom: 0,
    right: 0,
    x: 0,
    y: 0
  }); // keep all state in a ref

  const state = useRef({
    element: null,
    scrollContainers: null,
    resizeObserver: null,
    lastBounds: bounds
  }); // set actual debounce values early, so effects know if they should react accordingly

  const scrollDebounce = debounce$1 ? typeof debounce$1 === 'number' ? debounce$1 : debounce$1.scroll : null;
  const resizeDebounce = debounce$1 ? typeof debounce$1 === 'number' ? debounce$1 : debounce$1.resize : null; // make sure to update state only as long as the component is truly mounted

  const mounted = useRef(false);
  useEffect(() => {
    mounted.current = true;
    return () => void (mounted.current = false);
  }); // memoize handlers, so event-listeners know when they should update

  const [forceRefresh, resizeChange, scrollChange] = useMemo(() => {
    const callback = () => {
      if (!state.current.element) return;
      const {
        left,
        top,
        width,
        height,
        bottom,
        right,
        x,
        y
      } = state.current.element.getBoundingClientRect();
      const size = {
        left,
        top,
        width,
        height,
        bottom,
        right,
        x,
        y
      };
      Object.freeze(size);
      if (mounted.current && !areBoundsEqual(state.current.lastBounds, size)) set(state.current.lastBounds = size);
    };

    return [callback, resizeDebounce ? debounce(callback, resizeDebounce) : callback, scrollDebounce ? debounce(callback, scrollDebounce) : callback];
  }, [set, scrollDebounce, resizeDebounce]); // the ref we expose to the user

  const ref = useCallback(node => {
    if (!node || node === state.current.element) return;
    removeListeners(state, scrollChange);
    state.current.element = node;
    state.current.scrollContainers = findScrollContainers(node);
    addListeners(state, scrollChange, scroll);
  }, [scroll, scrollChange]); // add general event listeners

  useOnWindowScroll(scrollChange, Boolean(scroll));
  useOnWindowResize(resizeChange); // respond to changes that are relevant for the listeners

  useEffect(() => {
    removeListeners(state, scrollChange);
    addListeners(state, scrollChange, scroll);
  }, [scroll, scrollChange, resizeChange]); // remove all listeners when the components unmounts

  useEffect(() => () => removeListeners(state, scrollChange), []);
  return [ref, bounds, forceRefresh];
} // Adds native resize listener to window


function useOnWindowResize(onWindowResize) {
  useEffect(() => {
    const cb = onWindowResize;
    window.addEventListener('resize', cb);
    return () => void window.removeEventListener('resize', cb);
  }, [onWindowResize]);
}

function useOnWindowScroll(onScroll, enabled) {
  useEffect(() => {
    if (enabled) {
      const cb = onScroll;
      window.addEventListener('scroll', cb, {
        capture: true,
        passive: true
      });
      return () => void window.removeEventListener('scroll', cb, true);
    }
  }, [onScroll, enabled]);
} // Returns a list of scroll offsets


function findScrollContainers(element) {
  const result = [];
  if (!element || element === document.body) return result;
  const {
    overflow,
    overflowX,
    overflowY
  } = window.getComputedStyle(element);
  if ([overflow, overflowX, overflowY].some(prop => prop === 'auto' || prop === 'scroll')) result.push(element);
  return [...result, ...findScrollContainers(element.parentElement)];
} // cleanup current scroll-listeners / observers


function removeListeners(state, scrollChange) {
  if (state.current.scrollContainers) {
    state.current.scrollContainers.forEach(element => element.removeEventListener('scroll', scrollChange, true));
    state.current.scrollContainers = null;
  }

  if (state.current.resizeObserver) {
    state.current.resizeObserver.disconnect();
    state.current.resizeObserver = null;
  }
} // add scroll-listeners / observers


function addListeners(state, scrollChange, scroll) {
  if (!state.current.element) return;
  state.current.resizeObserver = new ResizeObserver(scrollChange);
  state.current.resizeObserver.observe(state.current.element);

  if (scroll && state.current.scrollContainers) {
    state.current.scrollContainers.forEach(scrollContainer => scrollContainer.addEventListener('scroll', scrollChange, {
      capture: true,
      passive: true
    }));
  }
} // Checks if element boundaries are equal


const keys = ['x', 'y', 'top', 'bottom', 'left', 'right', 'width', 'height'];

const areBoundsEqual = (a, b) => keys.every(key => a[key] === b[key]);

if (typeof module !== 'undefined' && Object.getOwnPropertyDescriptor && Object.getOwnPropertyDescriptor(module, 'exports').writable) {
  module.exports = useMeasure;
}

export default useMeasure;