Is it possible to ping a server from Javascript?

Question

I\'m making a web app that requires that I check to see if remote servers are online or not. When I run it from the command line, my page load goes up to a full 60s (for 8 e

Answer 1

If what you are trying to see is whether the server "exists", you can use the following:

function isValidURL(url) {
    var encodedURL = encodeURIComponent(url);
    var isValid = false;

    $.ajax({
      url: "http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20html%20where%20url%3D%22" + encodedURL + "%22&format=json",
      type: "get",
      async: false,
      dataType: "json",
      success: function(data) {
        isValid = data.query.results != null;
      },
      error: function(){
        isValid = false;
      }
    });

    return isValid;
}

This will return a true/false indication whether the server exists.

If you want response time, a slight modification will do:

function ping(url) {
    var encodedURL = encodeURIComponent(url);
    var startDate = new Date();
    var endDate = null;
    $.ajax({
      url: "http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20html%20where%20url%3D%22" + encodedURL + "%22&format=json",
      type: "get",
      async: false,
      dataType: "json",
      success: function(data) {
        if (data.query.results != null) {
            endDate = new Date();
        } else {
            endDate = null;
        }
      },
      error: function(){
        endDate = null;
      }
    });

    if (endDate == null) {
        throw "Not responsive...";
    }

    return endDate.getTime() - startDate.getTime();
}

The usage is then trivial:

var isValid = isValidURL("http://example.com");
alert(isValid ? "Valid URL!!!" : "Damn...");

Or:

var responseInMillis = ping("example.com");
alert(responseInMillis);