What I want:
My propose is to check if new content was added in a page (that I do not own), so I was thinking to make a script that save the last content added in a cookie and refresh the page every minute: If the cookie doesn't match the last content added, that would mean there is new content and I would receive a notification.
Let's try with pseudocode:
main_file:
include: functions.js;
cookie last_content_added= get_first_paragraph();
//Refresh script
do (every_minute){
page_reload();
}
when.page.reload.complete {
run script_check_content
}
functions.js
script_check_content{
var content_check = get_first_paragraph();
if (content_check == cookie[last_content_added])
{
//do nothing
}
else{
//new content was added
play.notification.mp3
cookie[last_content.added] = get_first_paragraph();
}
}
Am I not thinking in an easier solution for what I'm looking for?
I'm new to chrome extensions, if you could separate the code in different files like it was a real extension, I would appreciate very much.
I recommend to use 'chrome.tabs.query', use this to get all tabs that have the specified properties or all tabs if no properties are specified and 'chrome.tabs.executeScript' to inject the javascript code into a page that calls 'window.location.reload(). to refresh the page.
Here's a sample code to get the current tab and reload it using chrome.tab methods:
chrome.tabs.query({active: false, currentWindow: true}, function (arrayOfTabs) {
var code = 'window.location.reload();';
chrome.tabs.executeScript(arrayOfTabs[0].id, {code: code});
});
Also, include 'onCompleted' listener to listen when it is completely loaded and initialized.
chrome.webNavigation.onCompleted.addListener(function callback).
Take a look at MutationObserver, it provides a way to react to changes in a DOM. You can provide a callback to react to DOM changes and don't need to use a timer.
I'm using an <iframe> (I know, I know, ...) in my app (single-page application with ExtJS 4.2) to do file downloads because they contain lots of data and can take a while to generate the Excel file (we're talking anything from 20 seconds to 20 minutes depending on the parameters).
The current state of things is : when the user clicks the download button, he is "redirected" by Javascript (window.location.href = xxx) to the page doing the export, but since it's done in PHP, and no headers are sent, the browser continuously loads the page, until the file is downloaded. But it's not very user-friendly, because nothing shows him whether it's still loading, done (except the file download), or failed (which causes the page to actually redirect, potentially making him lose the work he was doing).
So I created a small non-modal window docked in the bottom right corner that contains the iframe as well as a small message to reassure the user. What I need is to be able to detect when it's loaded and be able to differenciate 2 cases :
No data : OK => Close window
Text data : Error message => Display message to user + Close window
But I tried all 4 events (W3Schools doc) and none is ever fired. I could at least understand that if it's not HTML data returned, it may not be able to fire the event, but even if I force an error to return text data, it's not fired.
If anyone know of a solution for this, or an alternative system that may fit here, I'm all ears ! Thanks !
EDIT : Added iframe code. The idea is to get a better way to close it than a setTimeout.
var url = 'http://mywebsite.com/my_export_route';
var ifr = $('<iframe class="dl-frame" src="'+url+'" width="0" height="0" frameborder="0"></iframe>');
ifr.appendTo($('body'));
setTimeout(function() {
$('.dl-frame').remove();
}, 3000);
I wonder if it would require some significant changes in both frontend and backend code, but have you considered using AJAX? The workflow would be something like this: user sends AJAX request to start file generating and frontend constantly polls it's status from the server, when it's done - show a download link to the user. I believe that workflow would be more straightforward.
Well, you could also try this trick. In parent window create a callback function for the iframe's complete loading myOnLoadCallback, then call it from the iframe with parent.myOnLoadCallback(). But you would still have to use setTimeout to handle server errors/connection timeouts.
And one last thing - how did you tried to catch iframe's events? Maybe it something browser-related. Have you tried setting event callbacks in HTML attributes directly? Like
<iframe onload="done()" onerror="fail()"></iframe>
That's a bad practice, I know, but sometimes job need to be done fast, eh?
UPDATE
Well, I'm afraid you have to spend a long and painful day with a JS debugger. load event should work. I still have some suggestions, though:
1) Try to set event listener before setting element's src. Maybe onload event fires so fast that it slips between creating element and setting event's callback
2) At the same time try to check if your server code plays nicely with iframes. I have made a simple test which attempts to download a PDF from Dropbox, try to replace my URL with your backed route's.
<script src="https://code.jquery.com/jquery-1.11.1.min.js"></script>
<iframe id="book"></iframe>
<button id="go">Request downloads!</button>
<script>
var bookUrl = 'https://www.dropbox.com/s/j4o7tw09lwncqa6/thinkpython.pdf';
$('#book').on('load', function(){
console.log('WOOT!', arguments);
});
$('#go').on('click', function(){
$('#book').attr('src', bookUrl);
});
</script>
UPDATE 2
3) Also, look at the Network tab of your browser's debugger, what happens when you set src to the iframe, it should show request and server's response with headers.
I've tried with jQuery and it worked just fine as you can see in this post.
I made a working example here.
It's basically this:
<iframe src="http://www.example.com" id="myFrame"></iframe>
And the code:
function test() {
alert('iframe loaded');
}
$('#myFrame').load(test);
Tested on IE11.
I guess I'll give a more hacky alternative to the more proper ways of doing it that the others have posted. If you have control over the PHP download script, perhaps you can just simply output javascript when the download is complete. Or perhaps redirect to a html page that runs javascript. The javascript run, can then try to call something in the parent frame. What will work depends if your app runs in the same domain or not
Same domain
Same domain frame can just use frame javascript objects to reference each other. so it could be something like, in your single page application you can have something like
window.downloadHasFinished=function(str){ //Global pollution. More unique name?
//code to be run when download has finished
}
And for your download php script, you can have it output this html+javascript when it's done
<script>
if(parent && parent.downloadHasFinished)
parent.downloadHasFinished("if you want to pass a data. maybe export url?")
</script>
Demo jsfiddle (Must run in fullscreen as the frames have different domain)
Parent jsfiddle
Child jsfiddle
Different Domains
For different domains, We can use postMessage. So in your single page application it will be something like
$(window).on("message",function(e){
var e=e.originalEvent
if(e.origin=="http://downloadphp.anotherdomain.com"){ //for security
var message=e.data //data passed if any
//code to be run when download has finished
}
});
and in your php download script you can have it output this html+javascript
<script>
parent.postMessage("if you want to pass data",
"http://downloadphp.anotherdomain.com");
</script>
Parent Demo
Child jsfiddle
Conclusion
Honestly, if the other answers work, you should probably use those. I just thought this was an interesting alternative so I posted it up.
You can use the following script. It comes from a project of mine.
$("#reportContent").html("<iframe id='reportFrame' sandbox='allow-same-origin allow-scripts' width='100%' height='300' scrolling='yes' onload='onReportFrameLoad();'\></iframe>");
Maybe you should use
$($('.dl-frame')[0].contentWindow.document).ready(function () {...})
Try this (pattern)
$(function () {
var session = function (url, filename) {
// `url` : URL of resource
// `filename` : `filename` for resource (optional)
var iframe = $("<iframe>", {
"class": "dl-frame",
"width": "150px",
"height": "150px",
"target": "_top"
})
// `iframe` `load` `event`
.one("load", function (e) {
$(e.target)
.contents()
.find("html")
.html("<html><body><div>"
+ $(e.target)[0].nodeName
+ " loaded" + "</div><br /></body></html>");
alert($(e.target)[0].nodeName
+ " loaded" + "\nClick link to download file");
return false
});
var _session = $.when($(iframe).appendTo("body"));
_session.then(function (data) {
var link = $("<a>", {
"id": "file",
"target": "_top",
"tabindex": "1",
"href": url,
"download": url,
"html": "Click to start {filename} download"
});
$(data)
.contents()
.find("body")
.append($(link))
.addBack()
.find("#file")
.attr("download", function (_, o) {
return (filename || o)
})
.html(function (_, o) {
return o.replace(/{filename}/,
(filename || $(this).attr("download")))
})
});
_session.always(function (data) {
$(data)
.contents()
.find("a#file")
.focus()
// start 6 second `download` `session`,
// on `link` `click`
.one("click", function (e) {
var timer = 6;
var t = setInterval(function () {
$(data)
.contents()
.find("div")
// `session` notifications
.html("Download session started at "
+ new Date() + "\n" + --timer);
}, 1000);
setTimeout(function () {
clearInterval(t);
$(data).replaceWith("<span class=session-notification>"
+ "Download session complete at\n"
+ new Date()
+ "</span><br class=session-notification />"
+ "<a class=session-restart href=#>"
+ "Restart download session</a>");
if ($("body *").is(".session-restart")) {
// start new `session`,
// on `.session-restart` `click`
$(".session-restart")
.on("click", function () {
$(".session-restart, .session-notification")
.remove()
// restart `session` (optional),
// or, other `session` `complete` `callback`
&& session(url, filename ? filename : null)
})
};
}, 6000);
});
});
};
// usage
session("http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf", "ECMA_JS.pdf")
});
jsfiddle http://jsfiddle.net/guest271314/frc82/
In regards to your comment about to get a better way to close it instead of setTimeout. You could use jQuery fadeOut option or any of the transitions and in the 'complete' callback remove the element. Below is an example you can dump right into a fiddle and only need to reference jQuery.
I also wrapped inside listener for 'load' event to not do the fade until the iFrame has been loaded as question originally was asking.
// plugin your URL here
var url = 'http://jquery.com';
// create the iFrame, set attrs, and append to body
var ifr = $("<iframe>")
.attr({
"src": url,
"width": 300,
"height": 100,
"frameborder": 0
})
.addClass("dl-frame")
.appendTo($('body'))
;
// log to show its part of DOM
console.log($(".dl-frame").length + " items found");
// create listener for load
ifr.one('load', function() {
console.log('iframe is loaded');
// call $ fadeOut to fade the iframe
ifr.fadeOut(3000, function() {
// remove iframe when fadeout is complete
ifr.remove();
// log after, should no longer exist in DOM
console.log($(".dl-frame").length + " items found");
});
});
If you are doing a file download from a iframe the load event wont fire :) I was doing this a week ago. The only solution to this problem is to call a download proxy script with a tag and then return that tag trough a cookie then the file is loaded. min while yo need to have a setInterval on the page witch will watch for that specific cookie.
// Jst to clearyfy
var token = new Date().getTime(); // ticks
$('<iframe>',{src:"yourproxy?file=somefile.file&token="+token}).appendTo('body');
var timers = [];
timers[timers.length+1] = setInterval(function(){
var _index = timers.length+1;
var cookie = $.cooke(token);
if(typeof cookie != "undefined"){
// File has been downloaded
$.removeCookie(token);
clearInterval(_index);
}
},400);
in your proxy script add the cookie with the name set to the string sent bay the token url parameter.
If you control the script in server that generates excel or whatever you are sending to iframe why don't you put a UID flag and store it in session with value 0, so... when iframe is created and server script is called just set UID flag to 1 and when script is finished (the iframe will be loaded) just put it to 2.
Then you only need a timer and a periodic AJAX call to the server to check the UID flag... if it's set to 0 the process doesn't started, if it's 1 the file is creating, and finally if it's 2 the process has been ended.
What do you think? If you need more information about this approach just ask.
What you are saying could be done for images and other media formats using $(iframe).load(function() {...});
For PDF files or other rich media, you can use the following Library:
http://johnculviner.com/jquery-file-download-plugin-for-ajax-like-feature-rich-file-downloads/
Note: You will need JQuery UI
You can use this library. The code snippet for you purpose would be something like:
window.onload = function () {
rajax_obj = new Rajax('',
{
action : 'http://mywebsite.com/my_export_route',
onComplete : function(response) {
//This will only called if you have returned any response
// instead of file from your export script
// In your case 2
// Text data : Error message => Display message to user
}
});
}
Then you can call rajax_obj.post() on your download link click.
Download
NB: You should add some header to your PHP script so it force file download
header('Content-Disposition: attachment; filename="'.$file.'"');
header('Content-Transfer-Encoding: binary');
There is two solutions that i can think of. Either you have PHP post it's progress to a MySQL table where from frontend will be pulling information from using AJAX calls to check up on the progress of the generation. Using somekind of unique key that is being generated when accessing the page would be ideal for multiple people generating excel files at the same time.
Another solution would be to use nodejs & then in PHP post the progress of the excel file using cURL or a socket to a nodejs service. Then when receiving updates from PHP in nodejs you simply write the progress of the excel file for the right socket. This will cut off some browser support though. Unless you go through with it using external libraries to bring websocket support for pretty much all browsers & versions.
Hope this answer helped. I was having the same issue previous year. Ended up doing AJAX polling having PHP post progress on the fly.
Try this:
Note: You should be on the same domain.
var url = 'http://mywebsite.com/my_export_route',
iFrameElem = $('body')
.append('<iframe class="dl-frame" src="' + url + '" width="0" height="0" frameborder="0"></iframe>')
.find('.dl-frame').get(0),
iDoc = iFrameElem.contentDocument || iFrameElem.contentWindow.document;
$(iDoc).ready(function (event) {
console.log('iframe ready!');
// do stuff here
});
In Lightswitch HTML client we have created a screen to display the work in progress for a particular business processes.
This is to be displayed on a big screen, much like when you go to Argos to collect your order. Here's a screenshot...
We are using some java script to refresh the page every 30 seconds.
setTimeout(function () {
window.location.reload(1);
}, 30000);
However, there are two issues with this.
The 'maximum number of results' text input by the user is lost on refresh.
It doesnt look nice to refresh the whole page.
Is it therefore possible to just trigger each query to reload instead of the entire page?
(The data is provided to LightSwitch by a WCF RIA Service)
In the JavaScript, use screen.MyList.load(). It will reload the list asynchronously.
Note that IntelliSense does not always suggest list names on the screen object but will recognize them if you type the name.
Combined with the setTimeout() method and the created screen event, it should work.
I had the same issue and finally found the solution. I added this in my created event:
myapp.BrowseMembers.created = function (screen) {
setInterval(function () {screen.Members.load(true);}, 1000);
};
Ii works, just the screen get flickering when reloading the data.
setTimeout will only trigger once but setInterval will trigger every 1 second.
I had the same problem with LightSwitch VS2012 Update 3,
for my case just invalidation is enough, so i can always work with a fresh entity.
This code runs once on entry screen and invalidates loaded entities every 30 seconds, and forces a refetch just when needed.
myapp.aaHome.created = function (screen) {
setInterval(function () {
screen.details.dataWorkspace.ApplicationData.Currencies._loadedEntities = {};
}, 30000);
};
I have a picture in a DIV on site abc.com which is hosted elsewhere, for example <IMG SRC="http://xyz.com/image.jpg">.
It loads fine, but, I need to update this every few seconds.
The majority of items to upload are local, but the following code will not work for remote pictures:
$('#rightpic').load('http://xyz.com/image.jpg', null);
By trying this, I am getting an error : ...is not allowed by Access-Control-Allow-Origin.
Can anyone recommend a better way of doing this?
Try this out, you want to actually change the src, not use the .load() function.
$('#rightpic').get(0).src = 'http://xyz.com/image.jpg';
.load uses an AJAX request, thus the same origin policy applies - which restricts cross-domain requests. Besides, it's not the best way to load images anyway. Also, setting the same url as src will often load images from the cache.
Instead, you should add a random query string value every request, like a timestamp, to "bust the cache"
var img = document.getElementById('rightpic');
//update every 10 seconds using time from epoch as random value
setInterval(function(){
var randomValue = new Date().getTime();
img.src = "http://example.com/image.jpg?t="+randomvalue;
},10000);
I'm using javascript to include some content served up from a php file on another server. However, this other service can sometimes get flaky and either take a long time to load or will not load at all.
Is there a way in JS to try to get the external data for x number of seconds before failing and displaying a "please try again" message?
<script type="text/javascript" src="htp://otherserver.com/myscript.php"></script>
Couple issues: you can use timeout thresholds with XMLHttpRequest (aka ajax), but then since it's on an otherserver.com you cannot use XMLHttpRequest (and support all A-grade browsers) due to the Same Origin Policy restriction.
If the script introduces any kind of global name (eg any variable name, function name, etc) You can try setTimeout to keep checking for it:
var TIMELIMIT = 5; // seconds until timeout
var start = new Date;
setTimeout(function() {
// check for something introduced by your external script.
// A variable, namespace or function name here is adequate:
var scriptIncluded = 'otherServerVariable' in window;
if(!scriptIncluded) {
if ((new Date - start) / 1000 >= TIMELIMIT) {
// timed out
alert("Please try again")
}
else {
// keep waiting...
setTimeout(arguments.callee, 100)
}
}
}, 100)
The problem as I see it is you cannot cancel the request for the script. Please someone correct me if I'm wrong but removing the <script> from the DOM will still leave the browser's request for the resource active. So although you can detect that the script is taking longer than x seconds to load, you can't cancel the request.
I think you may be out of luck.
The only way I can think of doing this is to create a proxy on another (PHP-enabled) server which will fetch the data for you, but will stop when a certain timeout limit has been reached (and it can just return an empty result).
This is purely, purely theoretical:
<script> tags can be dynamically inserted into the DOM, at which point the script will be fetched and processed. This dynamic script tag injection is how some achieve cross-domain "AJAX."
I would imagine you could declare a global variable var hasLoaded = false;. At the end of the script you are attempting to load you could set that variable to true hadLoaded=true;. After injecting the script tag into the DOM you could then kickoff a setTimeout() whose callback function checks to see if "hasLoaded" is set to true. If it isn't, you can assume the script has not yet loaded fully into the browser. If it has, you can assume it has loaded completely.
Again, this is theoretical, but if you test it be sure to report back, I'm very curious.
I think that the only way to do this is take the content of the file via ajax and then set a timer. If the request finishes before the timer you can evaluate the respons with eval(that's not the better solution anyway), otherwise you can stop the ajax request and write the error message.