hostReachable.js

function hostReachable() {

  // Handle IE and more capable browsers
  var xhr = new ( window.ActiveXObject || XMLHttpRequest )( "Microsoft.XMLHTTP" );
  var status;

  // Open new request as a HEAD to the root hostname with a random param to bust the cache
  xhr.open( "HEAD", "//" + window.location.hostname + "/?rand=" + Math.floor((1 + Math.random()) * 0x10000), false );

  // Issue request and handle response
  try {
    xhr.send();
    return ( xhr.status >= 200 && xhr.status < 300 || xhr.status === 304 );
  } catch (error) {
    return false;
  }

}

Hi,

Thank you for this simple gist.

If you have a port problem, or if you code on a "localhost:8888", try to use window.location.host instead of window.location.hostname

@Hettomei that will not work, see my answer in https://gist.github.com/cmpscabral/7626ae29475283d32771

Hi i am trying this on my local server and using xhr.open( "HEAD","http://www.google.com" , false ); and it is always returning false. KIndly help

@sumit read about CORS

// Open new request as a HEAD to the root hostname with a random param to bust the cache << Why do you have to bust the cache? And how is it going to bust the cache? Thanks!

And if you want to wait until online you can use this:

public waitUntilOnline(): any {

        return new window.Promise((resolve, reject) => {  

        	let interval: any = window.setInterval(() => {   

        		if (this.isOnline()) {   

        			window.clearInterval(interval);  
 
        			interval = undefined;   

        			resolve(true); 
  
        		}  else {   

        			console.log('Browser is still offine...');  
 
        		}   

        	}, 2500);   

        });   
}

this.waitUntilOnline().then((isOnline: boolean) => {
 //always returns true here. Do anything when the browser switches from offline to online
});