use-navigator-online/lib/index.umd.js

React Hooks to detect when your browser is online/offline.

(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory(require('react')) :
  typeof define === 'function' && define.amd ? define(['react'], factory) :
  (global = typeof globalThis !== 'undefined' ? globalThis : global || self, global.useNavigatorOnline = factory(global.React));
})(this, (function (react) { 'use strict';

  function useNavigatorOnline() {
    const supported = typeof window !== "undefined" && typeof navigator !== "undefined" && "onLine" in navigator;
    const [isOnline, setIsOnline] = react.useState({
      previous: supported ? navigator.onLine : false,
      current: supported ? navigator.onLine : false
    });
    react.useEffect(() => {
      if (supported) {
        const updateStatus = event => {
          setIsOnline({
            previous: isOnline.current,
            current: event.type === "online"
          });
        };

        window.addEventListener("offline", updateStatus);
        window.addEventListener("online", updateStatus);
        return () => {
          window.removeEventListener("offline", updateStatus);
          window.removeEventListener("online", updateStatus);
        };
      }

      return () => {};
    }, [isOnline, supported]);
    return {
      backOnline: !isOnline.previous && isOnline.current,
      backOffline: isOnline.previous && !isOnline.current,
      isOnline: isOnline.current,
      isOffline: !isOnline.current
    };
  }

  return useNavigatorOnline;

}));