use to test ping.

ping.js

function ping(ip) {
  var img = new Image();
	var start = new Date().getTime();
	img.src = 'http://' + ip + '?t=' + start;
	var flag = false;

	img.onload = function () {
		flag = true;
		console.log('ok');
	}

	img.onerror = function () {
		flag = true;
		console.log('ok');
	}

	var timer = setTimeout(function () {
		if (!flag) {
			flag = false;
			console.log('failed');
		}
	}, 1500);
}

ping('192.168.1.1');