local host discovery

HTML

Wait a few seconds while the scan happens...

<div id="hosts"></div>

JavaScript

// in testing it took:
// * 5ms to error on a host that is not up
// * 3055ms to error on a host that is up
//
// if your network has different timing characteristics you may need to modify this value.

var cutoff = (5 + 3055)/2.0;

function img_load_time(link) {
	var startTime = new Date().getTime();
	var img = new Image();
  img.onerror = function() {
  	var loadtime = new Date().getTime() - startTime;
    var result = (loadtime < cutoff) ? "UP" : "DOWN";
  	var node = document.createElement("li");
		var textnode = document.createTextNode(link + " " + result);
		node.appendChild(textnode);
    document.getElementById("hosts").appendChild(node);
    next();
  }
  img.src = link;
}

var i = 0;
function next() {
  if(i > 20) return;
	img_load_time("https://192.168.1."+i+"/");
  i++;
}

next();