Unable to detect no internet connection, in cordova app - javascript

I have been searching on how to check internet connection for my cordova app(targeting android at the moment). I have tried the following:
$.ajax("rss file url", {
contentType: "application/json; charset=utf-8",
dataType: 'jsonp',
crossDomain: true
})
.done(function (data, textStatus, jqXHR) {
//get rss
})
.fail(function (jqXHR, textStatus, errorThrown) {
//no internet alert
})
.always(function () {
//alert("complete");
});
Also I have tried
function doesConnectionExist() {
var xhr = new XMLHttpRequest();
var file = "file url";
var randomNum = Math.round(Math.random() * 10000);
xhr.open('HEAD', file + "?rand=" + randomNum, false);
try {
xhr.send();
if (xhr.status >= 200 && xhr.status < 304) {
return true;
} else {
return false;
}
} catch (e) {
return false;
}
}
The problem is that these work absolutely fine in visual studio's ripple emulators, but when I debug on android device I am getting always getting no connection result. Eventhough, the device is connected to wi-fi.
My app works fine if I remove this check. But, I need to check internet connectivity as my app is basically a rss feed reader. Any help would be appreciated.
I have tried the solution mentioned here I have already posted the $.ajax code. The problem is that the solution works fine on the ripple emulators. But when I release build on an android device from VS15, I keep getting no internet connection results.

I would use
document.addEventListener("online", yourCallbackFunction, false);
Then set some sort of variable to true in your callback function.
There's a same event for "offline".
This way you can also handle what happens if the user drops connection while using your app.
Source: http://docs.phonegap.com/en/1.8.1/cordova_events_events.md.html#online

I used a JS Library called OnlineJs and it works just fine to detect online and offline status.
try this link :
http://pixelscommander.com/polygon/onlinejs

function doesConnectionExist() {
var xhr = new XMLHttpRequest();
var file = "file url";
var randomNum = Math.round(Math.random() * 10000);
connection=getConnectionStatus();
if(connection){
xhr.open('HEAD', file + "?rand=" + randomNum, false);
try {
xhr.send();
if (xhr.status >= 200 && xhr.status < 304) {
return true;
} else {
return false;
}
} catch (e) {
return false;
}
}
Now inside the getConnectionStatus check for the connection.
function getConnectionStatus() {
var networkState = navigator.connection.type;
var states = {};
states[Connection.UNKNOWN] = 'unknown';
states[Connection.ETHERNET] = 'ethernet';
states[Connection.WIFI] = 'wifi';
states[Connection.CELL_2G] = '2g';
states[Connection.CELL_3G] = '3g';
states[Connection.CELL_4G] = '4g';
states[Connection.CELL] = 'cellular';
states[Connection.NONE] = 'none';
if(networkState != 'none') {
return true;
} else {
return false;
}
}
the states[] array is for undeerstanding as to what all types of network information u can manipulate with .
Hope it helps.

Related

using SFTP in JSCH to upload files,I want to know how to display the progress about uploading files

my web page have a button to select the files,when the button clicked,it will send files data to webserver,then webserver will build a SFTP service which is built from JSCH,then the files will be sent to remote server.now I want to know how to develop the progress bar.I have already developed the progress bar when files send to web server.I try to develop the progress bar when files send to remote server but i failed. enter image description here
picture one is the process which sends files to webserver.
picture two is the process which sends files to remote server.
enter image description here
// here is code which sends files to webserver.
$(function() {
$('#inputButton').on('click', function() {
var fd = new FormData();
var files_upload_num = document.getElementById('fileToUpload').files.length;
if(files_upload_num == 0)
{
alert('请选择文件,完成上传!');
return;
}
for(let i=0;i<files_upload_num;i++)
fd.append("fileToUpload", document.getElementById('fileToUpload').files[i]);
$.ajax({
url: '<%=path%>/FileCl?method=submitFile',
type: 'post',
data: fd,
processData: false,
contentType: false,
xhr: function() {
var newxhr;
if (window.XMLHttpRequest) {
newxhr = new XMLHttpRequest();
} else {
// code for IE6, IE5
newxhr = new ActiveXObject("Microsoft.XMLHTTP");
}
newxhr.upload.onprogress = function(e) {
console.log(e)
var percent = ( (e.loaded / e.total).toFixed(2) ) * 100 + '%'
$('#progressBar').css('width', percent)
document.getElementById('progressBar').innerHTML = percent;
}
newxhr.addEventListener("load", uploadComplete, false);
newxhr.addEventListener("error", uploadFailed, false);
newxhr.addEventListener("abort", uploadCanceled, false);
return newxhr
},
success: function(res) {
console.log(res)
},
dataType: 'json'
})
})
})
//here is code which sends files to remote server.
JSch jSch = new JSch();
Session jSchSession = null;
ChannelSftp chSftp = null;
jSchSession = jSch.getSession(username, host, port);
jSchSession.setPassword(password);
Properties config = new Properties();
config.put("StrictHostKeyChecking", "no");
jSchSession.setConfig(config);
jSchSession.setTimeout(1000*10);
jSchSession.connect();
chSftp = (ChannelSftp)jSchSession.openChannel("sftp");
chSftp.connect();
chSftp.setFilenameEncoding("UTF-8");
sftpUtil sftpUtil = new sftpUtil(chSftp);
for (FileItem item : fileItemList) {
String filename = item.getName();
if (filename == null || filename.trim().equals("")) {
continue;
}
String id = UUID.randomUUID().toString().replace("-","");
id = id.substring(0,8);
File saveFile = new File(path,id+filename);
fileNameList.add(id+filename);
sftpUtil.upload("/home/liuyb/uploads",filename,item.getInputStream(),new uploadFileProgressMonitor(item.getSize()));
}

XMLHttpRequest - get value from URL and write it in a div

I have a div called totalvalue.
<div id="totalvalue"></div>
I wrote a function to get value from my PHP script (on the same server).
function totalvalue() {
var ajax5 = new XMLHttpRequest();
ajax5.onreadystatechange = function() {
if (ajax5.readyState == 4) {
totalvalue = (ajax5.responseText);
console.log(totalvalue);
document.getElementById("totalvalue").innerHTML = ajax5.responseText;
}
};
ajax5.open("GET", "totalvalue.php", true);
ajax5.send(null);
}
The php script does output a value.
Neither my console nor the div display the output.
This worked for me.
function test5() {
var ajax5 = new XMLHttpRequest();
ajax5.onreadystatechange = function() {
if (ajax5.readyState == 4) {
xxx5 = (ajax5.responseText);
console.log("this is the total value: "+xxx5);
if (xxx5 == 0) {
document.getElementById("totalvalue").innerHTML="Loading...";
} else {
document.getElementById("totalvalue").innerHTML="Total: "+xxx5;
}
}
};
ajax5.open("GET", "totalvalue.php", true);
ajax5.send(null);
}
I presume that where I write the div matter + there could have been an issue with the cache. I cannot tell for sure why the above just started working.
For simpler code, and better cross browser support, i would use jQuery.ajax like so:
$.ajax({
url: 'totalvalue.php',
success: function(data){
$('#totalvalue').html(data);
}
});
Read more about it in the documentation

jQuery/AJAX: Code works in Chrome but not IE

I'm working on a validation form, I'm sending the data from the html fields with JS pulling the validation with a php document and sending it back via AJAX, it works pretty fine in Chrome but not Internet Explorer (I'm testing it in IE9):
function Checkfiles() {
var fup = document.getElementById('flUpload');
var fileName = fup.value;
var ext = fileName.substring(fileName.lastIndexOf('.') + 1);
var chkext = ext.toLowerCase();
if(chkext=="gif" || chkext=="jpg" || chkext=="jpeg" || chkext=="png") { return true; } else { return false; }
} // Checkfiles
function Checksize() {
var iSize;
if ($("#flUpload")[0].files[0]){ iSize = ($("#flUpload")[0].files[0].size / 1024);}
if(Checkfiles()==true && iSize <= 51.200) { return true; } else { return false; }
} //Checksize
$(document).ready(function() {
$("#ff1").submit(function(e){
// prevent submit
e.preventDefault();
var email = document.getElementById("email").value;
var title = document.getElementById("title").value;
var url = document.getElementById("url").value;
var parametros = {"emaail":email, "tiitle":title, "uurl":url};
$.ajax({
data: parametros,
url: 'validate.php',
type: 'post',
context: this,
error: function (response) {
alert("An error has occurred! Try Again!");
},
success: function (response) {
if($.trim(response)=='b' && Checksize()==true) {
this.submit(); // submit, bypassing jquery bound event
}
else {
if (Checksize()==true) {
$("#ajax_call_val").html('<div id="validation"><ul>'+response+'</ul></div>');
} else {
if(response!='b') {
$("#ajax_call_val").html('<div id="validation"><ul>'+response+'<li>Only GIF, PNG, JPG images, smaller than 50 KB</li></ul></div>');
} else { $("#ajax_call_val").html('<div id="validation"><ul><li>Only GIF, PNG, JPG images, smaller than 50 KB</li></ul></div>'); }
}
}
}
});
});
});
Any wonder why is not working in IE? Thanks in advance.

Loading XML into a browser with jQuery

Does anyone know why the following code does not work in FireFox but does in IE (on the server) and the other way around locally?
function load_xml(msg) { //this function will load xml even used in IE or any other browser
if ( typeof msg == 'string') {
data = new ActiveXObject( 'Microsoft.XMLDOM');
data.async = false;
data.loadXML( msg);
} else {
data = msg;
}
return data;
}
function getTitle(letter) {
$('#wordle').html('');
jQuery.ajax({
type: "POST",
url: "wordle-list.dat",
dataType: ($.browser.msie) ? "text/xml" : "xml",
success: function(xml) {
var xml2 = load_xml(xml);
var i=0;
$(xml2).find('wordle').each(function(){
$(xml2).find('w').each(function(){ //can change to w:lt(50)
var tmpHold = $(this).text();
if (tmpHold.substring(0, 1) == letter) {
$('#wordle').append('<li class="w">'+$(this).text()+'</li>');
}
});
});
}
});
}
My guess is because you have ActiveX installed in IE on the server and not on firefox and vice versa on your machine. Though it's difficult to say from just the code. At what line does the code fail both on the server and on the client machine?
Try this:
function load_xml(msg) {
if ( typeof msg == 'string') {
if (window.DOMParser)//Firefox
{
parser=new DOMParser();
data=parser.parseFromString(msg,"text/xml");
}else{ // Internet Explorer
data=new ActiveXObject("Microsoft.XMLDOM");
data.async="false";
data.loadXML(msg);
}
} else {
data = msg;
}
return data;
}
FOR EVERYONE WONDERING:
It was because I had the file extension as .dat and the server was saying it was a binary mime type...

Is it possible to ping a server from Javascript?

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 entries, it will scale linearly with more).
I decided to go the route of pinging on the user's end. This way, I can load the page and just have them wait for the "server is online" data while browsing my content.
If anyone has the answer to the above question, or if they know a solution to keep my page loads fast, I'd definitely appreciate it.
I have found someone that accomplishes this with a very clever usage of the native Image object.
From their source, this is the main function (it has dependences on other parts of the source but you get the idea).
function Pinger_ping(ip, callback) {
if(!this.inUse) {
this.inUse = true;
this.callback = callback
this.ip = ip;
var _that = this;
this.img = new Image();
this.img.onload = function() {_that.good();};
this.img.onerror = function() {_that.good();};
this.start = new Date().getTime();
this.img.src = "http://" + ip;
this.timer = setTimeout(function() { _that.bad();}, 1500);
}
}
This works on all types of servers that I've tested (web servers, ftp servers, and game servers). It also works with ports. If anyone encounters a use case that fails, please post in the comments and I will update my answer.
Update: Previous link has been removed. If anyone finds or implements the above, please comment and I'll add it into the answer.
Update 2: #trante was nice enough to provide a jsFiddle.
http://jsfiddle.net/GSSCD/203/
Update 3: #Jonathon created a GitHub repo with the implementation.
https://github.com/jdfreder/pingjs
Update 4: It looks as if this implementation is no longer reliable. People are also reporting that Chrome no longer supports it all, throwing a net::ERR_NAME_NOT_RESOLVED error. If someone can verify an alternate solution I will put that as the accepted answer.
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
}
}
you can try this:
put ping.html on the server with or without any content, on the javascript do same as below:
<script>
function ping(){
$.ajax({
url: 'ping.html',
success: function(result){
alert('reply');
},
error: function(result){
alert('timeout/error');
}
});
}
</script>
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)
You can't do regular ping in browser Javascript, but you can find out if remote server is alive by for example loading an image from the remote server. If loading fails -> server down.
You can even calculate the loading time by using onload-event. Here's an example how to use onload event.
Pitching in with a websocket solution...
function ping(ip, isUp, isDown) {
var ws = new WebSocket("ws://" + ip);
ws.onerror = function(e){
isUp();
ws = null;
};
setTimeout(function() {
if(ws != null) {
ws.close();
ws = null;
isDown();
}
},2000);
}
Update: this solution does not work anymore on major browsers, since the onerror callback is executed even if the host is a non-existent IP address.
To keep your requests fast, cache the server side results of the ping and update the ping file or database every couple of minutes(or however accurate you want it to be). You can use cron to run a shell command with your 8 pings and write the output into a file, the webserver will include this file into your view.
The problem with standard pings is they're ICMP, which a lot of places don't let through for security and traffic reasons. That might explain the failure.
Ruby prior to 1.9 had a TCP-based ping.rb, which will run with Ruby 1.9+. All you have to do is copy it from the 1.8.7 installation to somewhere else. I just confirmed that it would run by pinging my home router.
There are many crazy answers here and especially about CORS -
You could do an http HEAD request (like GET but without payload).
See https://ochronus.com/http-head-request-good-uses/
It does NOT need a preflight check, the confusion is because of an old version of the specification, see
Why does a cross-origin HEAD request need a preflight check?
So you could use the answer above which is using the jQuery library (didn't say it) but with
type: 'HEAD'
--->
<script>
function ping(){
$.ajax({
url: 'ping.html',
type: 'HEAD',
success: function(result){
alert('reply');
},
error: function(result){
alert('timeout/error');
}
});
}
</script>
Off course you can also use vanilla js or dojo or whatever ...
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);
const ping = (url, timeout = 6000) => {
return new Promise((resolve, 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(() => resolve(true))
.catch(() => resolve(false));
setTimeout(() => {
resolve(false);
}, timeout);
} catch (e) {
reject(e);
}
});
};
use like this:
ping('https://stackoverflow.com/')
.then(res=>console.log(res))
.catch(e=>console.log(e))
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/
let webSite = 'https://google.com/'
https.get(webSite, function (res) {
// If you get here, you have a response.
// If you want, you can check the status code here to verify that it's `200` or some other `2xx`.
console.log(webSite + ' ' + res.statusCode)
}).on('error', function(e) {
// Here, an error occurred. Check `e` for the error.
console.log(e.code)
});;
if you run this with node it would console log 200 as long as google is not down.
You can run the DOS ping.exe command from javaScript using the folowing:
function ping(ip)
{
var input = "";
var WshShell = new ActiveXObject("WScript.Shell");
var oExec = WshShell.Exec("c:/windows/system32/ping.exe " + ip);
while (!oExec.StdOut.AtEndOfStream)
{
input += oExec.StdOut.ReadLine() + "<br />";
}
return input;
}
Is this what was asked for, or am i missing something?
just replace
file_get_contents
with
$ip = $_SERVER['xxx.xxx.xxx.xxx'];
exec("ping -n 4 $ip 2>&1", $output, $retval);
if ($retval != 0) {
echo "no!";
}
else{
echo "yes!";
}
It might be a lot easier than all that. If you want your page to load then check on the availability or content of some foreign page to trigger other web page activity, you could do it using only javascript and php like this.
yourpage.php
<?php
if (isset($_GET['urlget'])){
if ($_GET['urlget']!=''){
$foreignpage= file_get_contents('http://www.foreignpage.html');
// you could also use curl for more fancy internet queries or if http wrappers aren't active in your php.ini
// parse $foreignpage for data that indicates your page should proceed
echo $foreignpage; // or a portion of it as you parsed
exit(); // this is very important otherwise you'll get the contents of your own page returned back to you on each call
}
}
?>
<html>
mypage html content
...
<script>
var stopmelater= setInterval("getforeignurl('?urlget=doesntmatter')", 2000);
function getforeignurl(url){
var handle= browserspec();
handle.open('GET', url, false);
handle.send();
var returnedPageContents= handle.responseText;
// parse page contents for what your looking and trigger javascript events accordingly.
// use handle.open('GET', url, true) to allow javascript to continue executing. must provide a callback function to accept the page contents with handle.onreadystatechange()
}
function browserspec(){
if (window.XMLHttpRequest){
return new XMLHttpRequest();
}else{
return new ActiveXObject("Microsoft.XMLHTTP");
}
}
</script>
That should do it.
The triggered javascript should include clearInterval(stopmelater)
Let me know if that works for you
Jerry
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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