How to check port availability in client-side JavaScript?
Question
是否可以在JavaScript中（在浏览器中）检测防火墙或路由器是否禁用了端口？
3 answers
solution1
5 2012-03-27 07:28:41
No, with pure javascript this is not possible (aside of making http requests to the specific ports, but those results mean little), what you can do however is check from the outside (in other words your server) whether the specific port is open. Another option would be to use a java applet or browser plugin which could do this for you if you really need it, in which case there are various open source tools which you could probably port if you have the necessary experience with those. Do note however that this isn't exactly user friendly. (Either way, it would be useful if you would describe the exact scenario where you need this, as there might be an altogether different solution.)
solution2
4 2012-03-27 07:26:08
You can only see if the expected response is there or not.
One has to stay in the boundaries of HTTP when using javascript.
Of course you can send an Ajax request on whatever port of server and see if you get an error. If you want to check port for current machine then probably sending a request on "localhost:843" could help.
But the error could be of some other reasons and not necessarily firewall issue.
We need more information to help you out.
solution3
3 2012-04-08 21:30:11
If you are flexible enough to use jQuery, then see this Answer by me . This will not only check the availability of port, but also whether a success response code 200 is coming from the remote (or any , I meant it supports cross-domain also) server. Also giving the solution here. I will be checking here for port 843.
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<script type="text/javascript" src="jquery-1.7.2-min.js"></script>
</head>
<body>
<script type"text/javascript">
var isAccessible = null;
function checkConnection() {
/*make sure you host a helloWorld HTML page in the following URL, so that requests are succeeded with 200 status code*/
var url = "http://yourserverIP:843/test/hello.html" ;
$.ajax({
url: url,
type: "get",
cache: false,
dataType: 'jsonp', // it is for supporting crossdomain
crossDomain : true,
asynchronous : false,
jsonpCallback: 'deadCode',
timeout : 1500, // set a timeout in milliseconds
complete : function(xhr, responseText, thrownError) {
if(xhr.status == "200") {
isAccessible = true;
success(); // yes response came, execute success()
}
else {
isAccessible = false;
failure(); // this will be executed after the request gets timed out due to blockage of ports/connections/IPs
}
}
});
}
$(document).ready( function() {
checkConnection(); // here I invoke the checking function
});
</script>
</body>
</html>
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.