Is it possible to ping a server from Javascript?

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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

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执笔经年

2020-11-22 04:44

Ping is ICMP, but if there is any open TCP port on the remote server it could be achieved like this:

function ping(host, port, pong) {

  var started = new Date().getTime();

  var http = new XMLHttpRequest();

  http.open("GET", "http://" + host + ":" + port, /*async*/true);
  http.onreadystatechange = function() {
    if (http.readyState == 4) {
      var ended = new Date().getTime();

      var milliseconds = ended - started;

      if (pong != null) {
        pong(milliseconds);
      }
    }
  };
  try {
    http.send(null);
  } catch(exception) {
    // this is expected
  }

}

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日久生厌

2020-11-22 04:46
You can't directly "ping" in javascript. There may be a few other ways:
- Ajax
- Using a java applet with isReachable
- Writing a serverside script which pings and using AJAX to communicate to your serversidescript
- You might also be able to ping in flash (actionscript)
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野趣味

2020-11-22 04:46

const ping = (url, timeout = 6000) => {
  return new Promise((reslove, reject) => {
    const urlRule = new RegExp('(https?|ftp|file)://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+[-A-Za-z0-9+&@#/%=~_|]');
    if (!urlRule.test(url)) reject('invalid url');
    try {
      fetch(url)
        .then(() => reslove(true))
        .catch(() => reslove(false));
      setTimeout(() => {
        reslove(false);
      }, timeout);
    } catch (e) {
      reject(e);
    }
  });
};

use like this:

ping('https://stackoverflow.com/')
  .then(res=>console.log(res))
  .catch(e=>console.log(e))

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借酒劲吻你

2020-11-22 04:47

I don't know what version of Ruby you're running, but have you tried implementing ping for ruby instead of javascript? http://raa.ruby-lang.org/project/net-ping/

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夕颜

2020-11-22 04:48

You could try using PHP in your web page...something like this:

<html><body>
<form method="post" name="pingform" action="<?php echo $_SERVER['PHP_SELF']; ?>">
<h1>Host to ping:</h1>
<input type="text" name="tgt_host" value='<?php echo $_POST['tgt_host']; ?>'><br>
<input type="submit" name="submit" value="Submit" >
</form></body>
</html>
<?php

$tgt_host = $_POST['tgt_host'];
$output = shell_exec('ping -c 10 '. $tgt_host.');

echo "<html><body style=\"background-color:#0080c0\">
<script type=\"text/javascript\" language=\"javascript\">alert(\"Ping Results: " . $output . ".\");</script>
</body></html>";

?>

This is not tested so it may have typos etc...but I am confident it would work. Could be improved too...

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粉色の甜心

2020-11-22 04:49

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);

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