My DiaryHub.vb has the following:
Imports Microsoft.AspNet.SignalR
Imports Microsoft.AspNet.SignalR.Hubs
Namespace UIS
<HubName("DiaryHub")>
Public Class DiaryHub
Inherits Hub
Public Sub PostDiaryHeadline()
' Call the addNewMessageToPage method to update clients.
Clients.All.addNewDiaryHeadlineToPage()
End Sub
End Class
End Namespace
My Home/Index window has the following code to initiate/configure SignalR.
$(function () {
// Save the reference to the SignalR hub
var dHub = $.connection.DiaryHub;
// Invoke the function to be called back from the server
// when changes are detected
// Create a function that the hub can call back to display new diary Headline entry.
dHub.client.addNewDiaryHeadlineToPage = function () {
// refresh the Headline Entries to the page.
outputHLDiaryEntries();
};
// Start the SignalR client-side listener
$.connection.hub.start().done(function () {
// Do here any initialization work you may need
outputHLDiaryEntries();
});
})
The code works and on launch the Headline diary entries are displayed.
I also have a button that opens a Kendo window as a modal with a form for adding new diary entries using this function:
function openAddWindow() {
var addWindow = $("#window").data("kendoWindow");
addWindow.refresh({
url: "Home/AddDiaryEntry/"
});
addWindow.open();
addWindow.center();
}
I then have the following Javascript in my AddDiaryEntry page:
function createDiaryEntry() {
var validFlag = true;
var errorMsg = "";
//Validate New Diary Entry
// removed for brevity...
if (validFlag) {
//data is valid
//get value of checkbox
var cbValue = ($("#addNew_dHeadline").is(':checked')) ? true : false;
//clear error area
$('#errorArea').html("");
var response = ''
$.ajax({
url: 'Home/SaveDiaryEntry',
type: 'POST',
data: {
dDate: $("#addNew_dDate").text(),
dCreatedBy: $("#addNew_dCreatedBy").text(),
dName: '#AppShort',
dTeam: teamValue.value(),
dType: typeValue.value(),
dRef: $("#addNew_dREF").val(),
dHeadline: cbValue,
dServer: multiSelect.value(),
dComment: editor.value()
},
success: function (result) {
response = result;
alert(response);
},
error: function (XMLHttpRequest, textStatus, errorThrown) {
response = "err--" + XMLHttpRequest.status + " -- " + XMLHttpRequest.statusText + " -- " + errorThrown;
alert(response);
}
});
//close window
var addWindow = $("#window").data("kendoWindow");
addWindow.close();
//if headline entry call SignalR post function to refresh diary entries
if (cbValue) {
// reference to the SignalR hub
var dHub = $.connection.DiaryHub;
// function to update all clients
dHub.client.PostDiaryHeadline(); //THIS IS A FUNCTION IN DiaryHub.vb
}
} else {
//error in data
var out = '<ul class="error">' + errorMsg + '</ul>';
// display errors
$('#errorArea').html(out);
}
}
The code works fine - validates the data, saves data to database. The issue I'm having is when I try to call dHub.client.PostDiaryHeadline() to invoke the SignalR function. I get the error: JavaScript runtime error: Object doesn't support property or method 'PostDiaryHeadline'
How do I call the function? Should I call the function before I close the modal window?
From what I can see your actually expecting a response rather than a server call.
adding server will fire a request.
if (cbValue) {
// reference to the SignalR hub
var dHub = $.connection.DiaryHub;
// function to update all clients
dHub.server.PostDiaryHeadline(); //THIS IS A FUNCTION IN DiaryHub.vb
}
Your already receiving the response here:
dHub.client.addNewDiaryHeadlineToPage = function () {
// refresh the Headline Entries to the page.
outputHLDiaryEntries();
};
//EDIT
There seems to be slight issues through out, so apart from the above(which needs fixing).
On the hub name (backend) replace with: <HubName("diaryHub")>
In your JS replace with: var dHub = $.connection.diaryHub;
Finally in your createDiaryEntry(); body should look like so:
$.connection.hub.start().done(function () {
// Do here any initialization work you may need
if (cbValue) {
// reference to the SignalR hub
var dHub = $.connection.diaryHub;
// function to update all clients
dHub.server.postDiaryHeadline(); //THIS IS A FUNCTION IN DiaryHub.vb
}
});
There are a few SignalR issues but that should get you on the right path.
Most SignalR issues stem from case sensitivity and structuring. All very common.
Should be the last issue, replace with: dHub.server.postDiaryHeadline();
lower case "p"
I'm working on an application that should be sending a post request to an internal page that does a certain calculation
When pressing a button, the page(dashboard.php) prints the content of the other page(calculate_salary.php)
here's my js code so far:
<script language="JavaScript" type="text/javascript">
function getXmlHttpRequestObject() {
return new XMLHttpRequest();
}
var receiveReq = getXmlHttpRequestObject();
function sayHello() {
if (receiveReq.readyState == 4 || receiveReq.readyState == 0) {
var start_date = $("#start_date").val();
var end_date = $("#end_date").val();
receiveReq.open("GET", 'calculate_salary.php', true);
receiveReq.onreadystatechange = handleSayHello;
receiveReq.send(null);
}
}
function handleSayHello() {
if (receiveReq.readyState == 4) {
document.getElementById('span_result').innerHTML = receiveReq.responseText;
}
}
</script>
I want to send over the values in start_date and end_date to the calculate_salary.php page
I will use that calculate page to perform some sql statements and return the result back.
How can I create this request?
POST is not an absolute necessity, I'm willing to use other techniques (js, php) to get the job done
thanks
You can use ajax instead
$.ajax({
url:"calculate_salary.php",
type:"POST",
data:{
start_date = $("#start_date").val(),
end_date = $("#end_date").val()
},
success:function(response){
$('#span_result').html(response);
}
});
You can read more about $.ajax and $.post
You have to generate querystring with url like so:
var url = 'calculate_salary.php?start_date='+start_date+'&end_date='+end_date;
receiveReq.open("POST", url, true);
Because you are not sending values that is why you are not receiving values on server side.
Another example you can find here:
How do I pass along variables with XMLHTTPRequest
Also check into this:
http://devzone.co.in/jquery-serialize-function-ajax-post-bigger-html-forms/
I'm using a framework called PartialJS that follows a MVC architecture to build a webApp that will verify a user's input and make a request to an API and render the API response.
I'm not sure how to redirect the user to the rendered page after verification and API call has finished. Where should the page redirect and API calls be made?
Here's a quick breakdown of what the user will see with 'bullet' marks denoting what happens in the backend:
User presented with a form and fills information
exports.onValidation() called via a serialized JSON to verify that
all fields completed accurately (triggered by a button), done without
a page refresh.
API call is made with user's information, will not return until response is received and parsed
Form rendered with decoded JSON response from external API
I have tried using this in the 'view.html' page but the page redirects before verification.
<buttononclick="window.location='http://www.CaliCoder.com/results';">Submit</button>
<script type="text/javascript">
$(document).ready(function() {
$('button').bind('click', function() {
$.post('/', $('#f').serialize(), function(d) {
var err = $('#error');
if (d instanceof Array) {
err.empty();
d.forEach(function(o) {
err.append('<div>' + o.error + '</div>');
});
err.show();
return;
};
$('#f').trigger('reset');
err.empty();
err.show().html('SUCCESS! Please wait while the request is being made')
});
});
});
</script>
Here's what happens in the 'controller.js' end of things.
function json_form() {
var self = this;
var error = self.validate(self.post, ['intersection', 'hours', 'minutes', 'phone'])
if (error.hasError()) {
self.json(error);
return;
}
// save to database
var db = self.database('forms');
db.insert(self.post);
self.json({ r: true });
}
function get_routes(hours, minutes, intersection) {
//The following code makes a call that returns an array with data to be rendered by another view controller.
var stops = this.module('cumtd').GetStopsBySearch('springfied busey');
}
Thanks for reading! Sorry for sounding confusing, I'm new to JS and Node programming. :(
You have problem in clide-side JavaScript, solution:
HTML:
<button>Submit</button>
JavaScript:
$(document).ready(function() {
$('button').bind('click', function() {
$.post('/', $('#f').serialize(), function(d) {
var err = $('#error');
if (d instanceof Array) {
err.empty();
d.forEach(function(o) {
err.append('<div>' + o.error + '</div>');
});
err.show();
return;
};
$('#f').trigger('reset');
err.empty();
err.show().html('SUCCESS! Please wait while the request is being made');
// HERE REDIRECT:
setTimeout(function() {
window.location.href = 'http://www.CaliCoder.com/results';
}, 3000);
});
});
});
I have created the following JavaScript function to load images of a vehicle, or load the alternate image if it is not available. The problem is that this page is 1kb, meanwhile it has to load the entire jquery library at 85+kb just for this one function. So my question is, is there some way to accomplish the same without having to load the jQuery library?
function GetImages() {
var Query = location.search;
//If query exists
if ((Query != "") && (Query != "?")){
var chunks = Query.split("=");
//If passed the right parameter
if (chunks[0] == "?unit") {
var Unit = chunks[1];
for (var i=1; i<11; i++) {
var unitimageURL = "/pics/"+Unit+"-"+i+".png";
$.ajax({
type: 'HEAD',
url: unitimageURL,
async: false,
success: function() {
$('.pictures').append("<img src="+unitimageURL+" width=150 height=90 alt='Unit "+Unit+" Picture "+i+"'> ");
if ((i == 4) || (i ==8)) {
$('.pictures').append("<br>");
}
},
error: function() {
$('.pictures').append("<img src=nopic2.png width=150 height=90 alt='Unit "+Unit+" Picture "+i+"'> ");
if ((i == 4) || (i ==8)) {
$('.pictures').append("<br>");
}
}
});
}
}
}
else {
alert("No query");
}
}
Yes, there is a way - the good old var oRequest = new XMLHttpRequest(); way!
Don't forget to to set all the needed callbacks, check response statuses and everything will be fine.
To create a HEAD request, just specify "HEAD" as parameter to .open() method.
You will also need document.createElement() to append the results to your page (or you may use .innerHTML property as well.
Also, documentation like this http://www.tutorialspoint.com/ajax/what_is_xmlhttprequest.htm may be handy.
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...