基于rxjs + proxy代理的方式实现响应式观察，监听对象属性的变化(可以监听嵌套对象属性变化，新增、删除属性行为，及数组的变化)，自动实例化BehaivorSubject，并自动next更新。外部只需订阅响应式对象即可获取变更通知

Polyfills the ResizeObserver API and supports box size options from the latest spec

🏯 PositionObserver is a JavaScript tool that provides a way to asynchronously observe changes in the position of a target element within its viewport.

Resize observer for React

Reactive primitives for observing resizing of HTML elements.

Monitor if a component is inside the viewport, using IntersectionObserver API

Symbol.observable ponyfill

React MutateObserver Component

A React hook that allows you to use a ResizeObserver to measure an element's size.

Resize observer for React

An implementation and polyfill of the Resize Observer draft.

A polyfill for the Resize Observer API

A React hook for the IntersectionObserver API that uses a polyfill when the native API is not available

Detect if web fonts are available

TypeScript definitions for resize-observer-browser

A React hook that fires a callback whenever ResizeObserver detects a change to its size

React bindings for MobX. Create fully reactive components.

@vue/reactivity

Tracks the intersection of a DOM element and its containing element or the viewport.

A React Hooks package for mutation-observer