JSPM

  • ESM via JSPM
  • ES Module Entrypoint
  • Export Map
  • Keywords
  • License
  • Repository URL
  • TypeScript Types
  • README
  • Created
  • Published
  • Downloads 93551
  • Score
    100M100P100Q149562F
  • License MIT

Check if the internet connection is up

Package Exports

  • is-online
  • is-online/browser

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (is-online) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

is-online Build Status

Check if the internet connection is up

Works in Node.js and the browser (with browserify/webpack).

In the browser you have navigator.onLine, but it's useless as it only tells you if there's a local connection, and not whether the internet is accessible.

Install

$ npm install --save is-online

Usage

const isOnline = require('is-online');

isOnline().then(online => {
    console.log(online);
    //=> true
});

API

isOnline([options])

options

Type: Object

timeout

Type: number
Default: 2000

Milliseconds to wait for a server to respond.

hostnames

Type: string Array
Default: ['www.google.com', 'www.cloudflare.com', 'www.baidu.com', 'www.yandex.ru']

One or more hosts to check.

How it works

In Node.js, we first contact one of the thirteen root servers and ask them to direct us to the servers which host the <root> zone (Which they are themselves). If the server answers, we return an online status.

If no satisfying answer is given within two seconds, we return an offline status. In the rare case where a firewall intercepts the packet and answers on its behalf, a second check is run which tries to connect to a series of popular web sites on port 80. If one of these connect, we return online, otherwise offline status.

In the browser, a sophisticated check like in Node.js is not possible because DNS and sockets are abstracted away. We use a check which requests an uncached favicon.ico on a series of popular websites. If one of these checks succeed, we return online status. If all the requests fail, we return offline status.

Maintainers

License

MIT © Sindre Sorhus