I'm having a really weird issue, I've developped a webextension that uses messaging between content script and background script (using chrome.runtime.connect) and nativemessaging.
The issue i'm facing is that when I install the extension (manually from the store beforehand and then connect to my website, everything works as expected, the chrome.runtime.connect works and returns a valid port to the background script.
But when i do an inline install of the extension from my website to get around the fact to have to navigate to have the content script in the webpage, i manually inject the content script into my page using
function injectContentScript() {
var s = document.createElement("script");
s.setAttribute("src", "chrome-extension://<extensionid>/content.js");
document.head.appendChild(s);
}
and the exact same content script but manually injected doesn't behave the same. chrome.runtime.connect returns a null object and chrome.runtime.lastError gives me
Could not establish connection. Receiving end does not exist.
I'm calling on the sender side (content.js - manually injected content script) chrome.runtime.connect(extensionID) where extension id is the id of the extension generated by the chrome webstore. And on the receiving side (background.js - extension background script) chrome.runtime.onConnect.addListener(onPortConnected);
I'm not really sure how to debug this issue, maybe it's a timing issue?
The background script is well executed even with the inline install (i've added logs and debugged it through the background.html in chrome extension manager)
Any help would be greatly appreciated!
You have two scenarios.
Your content script content.js is executed as normal upon navigation, as a content script defined in the manifest.
In this case, it executes in a special JS context attached to the page and reserved for your content scripts. See Execution Environment docs section for explanation. It is isolated from the webpage and is considered part of the extension (albeit with lower privileges).
When you connect from a content script, chrome.runtime.connect() is treated as internal communication between parts of the extension. So while you can provide the extension ID, it is not needed.
More importantly, the event raised in this case is chrome.runtime.onConnect.
Your supposed "inject content script immediately" code called from the webpage does something completely different.
Instead of creating a new execution context, the code is instead added directly to the page; it is not considered part of the extension and has no access to extension API.
Normally, a call to chrome.runtime.connect() would simply fail, as this is not a function exposed to webpages; however, you also declared externally_connectable, so it is exposed specifically to your webpage.
In this case, passing the extension ID is mandatory for the connect. You were doing this already, so the call was succeeding.
However, and that's what made it fail: the corresponding event is no longer onConnect, but onConnectExternal!
What you should be doing is:
Not mixing code that is run in very different contexts.
If you need communication from the webpage to background, always do it from the webpage, not sometimes-from-content-sometimes-from-page.
That way you only have to listen to onConnectExternal and it cuts out the need for a content script (if it was its only function).
See the docs as well: Sending messages from web pages.
You don't have to source the code from chrome-extension://<extensionid>/; you can directly add this to your website's code and potentially avoid web_accessible_resources.
And if you actually want to inject content scripts on first run, see for example this answer.
Related reading: How to properly handle chrome extension updates from content scripts
A website is running a jQuery script. I want to use a Chrome Extension to have the site run my own version of the jQuery script, and not the normal one.
So far, I've managed to make the chrome extension find where the website calls the normal script, and I've replaced it with my own:
document.querySelector("script[src^='website.com/originaljqueryscript']").src = 'myjqueryscript';
As a test, I made myjqueryscript the exact same script as the originaljqueryscript. I set the run_at in the manifest to run at document_end.
When I try to open the website with my script enabled, the console logged an error $(...).dialog is not a function. I think this is because jQuery is not loaded in my chrome extension. So then I found which version of jQuery the website is using, and added that to my chrome extension. Now I get this error: $(…).dialog is not a function I believe that error is due to a conflict between the two jQuerys that have been loaded (one on the website, one from my extension).
Am I on the right track, or is there a better way to replace a websites jQuery script with my own?
If this is for a very specific website, loading jQuery from a specific URL, you can use webRequest API to intercept the request to jQuery and redirect it to a file bundled in your extension. E.g.:
chrome.webRequest.onBeforeRequest.addListener(
function(details) { return {redirectUrl: chrome.runtime.getUrl("js/myjquery.js")}; },
{urls: ["https://example.com/js/jquery.js"]},
["blocking"]
);
(Note: this sample is very minimal; you may need to include and inspect request headers to make sure that the source page is your target site - you really don't want to replace a CDN-provided jQuery for all sites)
This assumes that the website does not use Subresource Integrity checks, however I believe that it will bypass a script-src Content Security Policy (redirect is transparent).
Note that .dialog() is part of jQuery UI, not core jQuery; the site presumably loads both, and you'll need to intercept both. It's possible that the site actually bundles them together.
i have a web project which works find in web. I want to transfer it into phonegap windows phone project .
Everything works fine but in a search option whenever i click in the search option it shows nothing showing a message "We are having trouble to display this message". N:B: this search option works properly in the web.
here is my search code:
<script src="https://code.jquery.com/jquery-2.1.1.min.js"></script>
<script src="js/materialize.min.js"></script>
<script src="js/init.js"></script>
<script>
var c=getCatalogue();
var bestNew=getBestNew();
$("#recherche").click(function(){
var v=$("#search").val();
window.localStorage.setItem("search",v);
if(v!="") routePage("recherche.html?search="+v);
});
</script>
I think problem is when i pass the value to another page that is "search="+v".
When i use if(v!="") routePage("recherche.html); instead of if(v!="") routePage("recherche.html?search="+v); then it works.
Try downloading and using JavaScript imports locally instead of fetching a remote version if not strictly necessary.
See:
<script src="https://code.jquery.com/jquery-2.1.1.min.js"></script>
Also phonegap.js should be included:
<script type="text/javascript" src="phonegap.js"></script>
You will need to move the JQuery source to a local file and update your script tag, like you have with materialize.min.js. Loading library JS from the network is not a good idea as it slows your app's startup down and also will cause it to fail when started in a situation where there is no network access.
Additionally Cordova/PhoneGap's Content Security Policy may be blocking remote script loads for security reasons - you don't state which PhoneGap/Cordova version you are using, but this may be a problem for you in Cordova 5. There's a tutorial on dealing with that here. You can configure around this by adjusting the Content Security Policy meta tag to allow script-src from other than "self" but I wouldn't recommend this.
When running in Cordova/PhoneGap you should also wait for the "deviceready" event before trying to do anything, to make sure that the framework is fully initialized and that you have access to call plugins.
Also instead of loading new pages you should architect your app so that it is a single page app and generates page fragments from templates as needed. Try looking at something like Handlebars for this unless you have another preferred solution. I have a complete demo app that uses this approach that you can look at the source for here.
How do I specify the following requirement in my html?
When the computer has access to Internet, the source of MathJax.js is https://c328740.ssl.cf1.rackcdn.com/mathjax/latest/MathJax.js;
When it is offline, and the system is Linux, the source is /MathJax/MathJax.js; if the system is Windows, it is /C:/MathJax/MathJax.js. (It would be even better if I can use environment variable in the local path.)
You can put MathJax in a location relative to your static HTML file:
<script src="https://c328740.ssl.cf1.rackcdn.com/mathjax/latest/MathJax.js"></script>
<script>
if( !window.MathJax ) {
document.write(
'<script type="text\/javascript" src="../lib/MathJax.js"><\/script>'
);
}
</script>
This way your implementation is independent of the OS.
Another option would be to set up the location according to your browser URL:
<script>
var url= location.protocol == 'http:'?
"https://c328740.ssl.cf1.rackcdn.com/mathjax/latest/MathJax.js" :
"../lib/MathJax.js";
document.write(
'<script type="text\/javascript" src="' + url + '"><\/script>'
);
</script>
These other pages might provide you with some new approaches to a solution.
The first one demos how you might chain a list of url's together, and continue trying to load the next script if the previous one fails.
Failover loading of .js from sequence of servers?
You would need to add your logic around Windows vs Linux into that.
Here are some ideas around detecting if the web page is running offline:
Detect that the Internet connection is offline?
If you could provide some more information about your application, I can probably come up with some better suggestions. Is this an application users install on their local computer? How do these JS files get onto people's C:\? What is installed when the app installs? How does it run? Is a local server installed as well? Or are the html pages just run from the file system in the web browser?
There are a few ways to include jQuery and jQuery UI and I'm wondering what people are using?
Google JSAPI
jQuery's site
your own site/server
another CDN
I have recently been using Google JSAPI, but have found that it takes a long time to setup an SSL connection or even only to resolve google.com. I have been using the following for Google:
<script src="https://www.google.com/jsapi"></script>
<script>
google.load('jquery', '1.3.1');
</script>
I like the idea of using Google so it's cached when visiting other sites and to save bandwidth from our server, but if it keeps being the slow portion of the site, I may change the include.
What do you use? Have you had any issues?
Edit: Just visited jQuery's site and they use the following method:
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script>
Edit2: Here's how I've been including jQuery without any problems for the last year:
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.4.3/jquery.min.js"></script>
The difference is the removal of http:. By removing this, you don't need to worry about switching between http and https.
Without a doubt I choose to have JQuery served by Google API servers. I didn't go with the jsapi method since I don't leverage any other Google API's, however if that ever changed then I would consider it...
First: The Google api servers are distributed across the world instead of my single server location: Closer servers usually means faster response times for the visitor.
Second: Many people choose to have JQuery hosted on Google, so when a visitor comes to my site they may already have the JQuery script in their local cache. Pre-cached content usually means faster load times for the visitor.
Third: My web hosting company charges me for the bandwidth used. No sense consuming 18k per user session if the visitor can get the same file elsewhere.
I understand that I place a portion of trust on Google to serve the correct script file, and to be online and available. Up to this point I haven't been disappointed with using Google and will continue this configuration until it makes sense not to.
One thing worth pointing out... If you have a mixture of secure and insecure pages on your site you might want to dynamically change the Google source to avoid the usual warning you see when loading insecure content in a secure page:
Here's what I came up with:
<script type="text/javascript">
document.write([
"\<script src='",
("https:" == document.location.protocol) ? "https://" : "http://",
"ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js' type='text/javascript'>\<\/script>"
].join(''));
</script>
UPDATE 9/8/2010 -
Some suggestions have been made to reduce the complexity of the code by removing the HTTP and HTTPS and simply use the following syntax:
<script type="text/javascript">
document.write("\<script src='//ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js' type='text/javascript'>\<\/script>");
</script>
In addition you could also change the url to reflect the jQuery major number if you wanted to make sure that the latest Major version of the jQuery libraries were loaded:
<script type="text/javascript">
document.write("\<script src='//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js' type='text/javascript'>\<\/script>");
</script>
Finally, if you don't want to use Google and would prefer jQuery you could use the following source path (keep in mind that jQuery doesn't support SSL connections):
<script type="text/javascript">
document.write("\<script src='http://code.jquery.com/jquery-latest.min.js' type='text/javascript'>\<\/script>");
</script>
One reason you might want to host on an external server is to work around the browser limitations of concurent connections to particular server.
However, given that the jQuery file you are using will likely not change very often, the browser cache will kick in and make that point moot for the most part.
Second reason to host it on external server is to lower the traffic to your own server.
However, given the size of jQuery, chances are it will be a small part of your traffic. You should probably try to optimize your actual content.
jQuery 1.3.1 min is only 18k in size. I don't think that's too much of a hit to ask on the initial page load. It'll be cached after that. As a result, I host it myself.
If you want to use Google, the direct link may be more responsive. Each library has the path listed for the direct file. This is the jQuery path
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js"></script>
Just reread your question, is there a reason your are using https? This is the script tag Google lists in their example
<script src="http://www.google.com/jsapi"></script>
I wouldn't want any public site that I developed to depend on any external site, and thus, I'd host jQuery myself.
Are you willing to have an outage on your site when the other (Google, jquery.com, etc.) goes down? Less dependencies is the key.
Pros: Host on Google has benefits
Probably faster (their servers are more optimised)
They handle the caching correctly - 1 year (we struggle to be allowed to make the changes to get the headers right on our servers)
Users who have already had a link to the Google-hosted version on another domain already have the file in their cache
Cons:
Some browsers may see it as XSS cross-domain and disallow the file.
Particularly users running the NoScript plugin for Firefox
I wonder if you can INCLUDE from Google, and then check the presence of some Global variable, or somesuch, and if absence load from your server?
There are a few issues here. Firstly, the async load method you specified:
<script type="text/javascript" src="https://www.google.com/jsapi"></script>
<script type="text/javascript">
google.load('jquery', '1.3.1');
google.setOnLoadCallback(function() {
// do stuff
});
</script>
has a couple of issues. Script tags pause the page load while they are retrieved (if necessary). Now if they're slow to load this is bad but jQuery is small. The real problem with the above method is that because the jquery.js load happens independently for many pages, they will finish loading and render before jquery has loaded so any jquery styling you do will be a visible change for the user.
The other way is:
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js"></script>
Try some simple examples like, have a simple table and change the background of the cells to yellow with the setOnLoadCallback() method vs $(document).ready() with a static jquery.min.js load. The second method will have no noticeable flicker. The first will. Personally I think that's not a good user experience.
As an example run this:
<html>
<head>
<title>Layout</title>
<style type="text/css">
.odd { background-color: yellow; }
</style>
</head>
<body>
<table>
<tr><th>One</th><th>Two</th></tr>
<tr><td>Three</td><td>Four</td></tr>
<tr><td>Five</td><td>Six</td></tr>
<tr><td>Seven</td><td>Nine</td></tr>
<tr><td>Nine</td><td>Ten</td></tr>
</table>
<script src="http://www.google.com/jsapi"></script>
<script>
google.load("jquery", "1.3.1");
google.setOnLoadCallback(function() {
$(function() {
$("tr:odd").addClass("odd");
});
});
</script>
</body>
</html>
You (should) see the table appear and then the rows go yellow.
The second problem with the google.load() method is that it only hosts a limited range of files. This is a problem for jquery since it is extremely plug-in dependent. If you try and include a jquery plugin with a <script src="..."> tag and google.load() the plug-in will probably fail with messages of "jQuery is not defined" because it hasn't loaded yet. I don't really see a way around this.
The third problem (with either method) is that they are one external load. Assuming you have some plugins and your own Javascript code you're up to a minimum of two external requests to load your Javascript. You're probably better off getting jquery, all relevant plug-ins and your own code and putting it into one minified file.
From Should You Use Google's Ajax Libraries API for Hosting?:
As to load times, you're actually
loading two scripts - the jsapi script
and the mootools script (the
compressed version from above). So
that is two connections, rather than
one. In my experience, I found that
the load time was actually 2-3 times
slower than loading from my own
personal shared server, even though it
was coming from Google, and my version
of the compressed file was a couple of
K larger than Google's. This, even
after the file had loaded and
(presumably) cached. So for me, since
the bandwidth doesn't matter much,
isn't going to matter.
Lastly you have the potential problem of a paranoid browser flagging the request as some sort of XSS attempt. It's not typically a problem with default settings but on corporate networks where the user may not have control over which browser they use let alone the security settings you may have a problem.
So in the end I can't really see me using the Google AJAX API for jQuery at least (the more "complete" APIs are a different story in some ways) much except to post examples here.
In addition to people who advices to host it on own server, I'd proposed to keep it on separate domain (e.g. static.website.com) to allow browsers to load it into separate from other content thread. This tip also works for all static stuff, say images and css.
I have to vote -1 for the libraries hosted on Google. They are collecting data, google analytics style, with their wrappers around these libraries. At a minimum, I don't want a client browser doing more than I'm asking it to do, much less anything else on the page. At worse, this is Google's "new version" of not being evil -- using unobtrusive javascript to gather more usage data.
Note: if they've changed this practice, super. But the last time I considered using their hosted libraries, I monitored the outbound http traffic on my site, and the periodic calls out to google servers were not something I expected to see.
I might be old-school about this, but I still frown on hotlinking. Maybe Google is the exception, but in general, it's really just good manners to host the files on your own server.
I will add this as a reason to locally host these files.
Recently a node in Southern California on TWC has not been able to resolve the ajax.googleapis.com domain (for users with IPv4) only so we are not getting the external files. This has been intermittant up until yesterday (now it is persistant.) Because it was intermittant, I was having tons of problems troubleshooting SaaS user issues. Spent countless hours trying to track why some users were having no issues with the software, and others were tanking. In my usual debugging process I'm not in the habit of asking a user if they have IPv6 turned off.
I stumbled on the issue because I myself was using this particular "route" to the file and also am using only IPV4. I discovered the issue with developers tools telling me jquery wasn't loading, then started doing traceroutes etc... to find the real issue.
After this, I will most likely never go back to externally hosted files because: google doesn't have to go down for this to become a problem, and... any one of these nodes can be compromised with DNS hijacking and deliver malicious js instead of the actual file. Always thought I was safe in that a google domain would never go down, now I know any node in between a user and the host can be a fail point.
I just include the latest version from the jQuery site: http://code.jquery.com/jquery-latest.pack.js It suits my needs and I never have to worry about updating.
EDIT:For a major web app, certainly control it; download it and serve it yourself. But for my personal site, I could not care less. Things don't magically disappear, they are usually deprecated first. I keep up with it enough to know what to change for future releases.
Here some useful resource, hope can help you to chose your CDN.
MS has recently add a new domain for delivery Libraries trough their CDN.
Old Format: http://ajax.microsoft.com/ajax/jQuery/jquery-1.5.1.js
New Format: http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.5.1.js
This should not send all cookies for microsoft.com.
http://www.asp.net/ajaxlibrary/cdn.ashx#Using_jQuery_from_the_CDN_11
Here some statistics about most popular technology used on the web across all technology.
http://trends.builtwith.com/
Hope can help you to choose.
If I am responsible for the 'live' site I better be aware of everything that is going
on and into my site. For that reason I host the jquery-min version myself either on the same server or a static/external server but either way a location where only I (or my program/proxy) can update the library after having verified/tested every change
In head:
(function() {
var jsapi = document.createElement('script'); jsapi.type = 'text/javascript'; jsapi.async = true;
jsapi.src = ('https:' == document.location.protocol ? 'https://' : 'http://') + 'www.google.com/jsapi?key=YOUR KEY';
(document.getElementsByTagName('head')[0] || document.getElementsByTagName('head')[0]).appendChild(jsapi);
})();
End of Body:
<script type="text/javascript">
google.load("jquery", "version");
</script>
I host it with my other js files on my own server, and, that's that point, combine and minify them (with django-compresser, here, but that's not the point) to be served as just one js file, with everything the site needs put into it. You'll need to serve your own js files anyway, so I see no reason to not add the extra jquery bytes there too - some more kbs are much more cheaper to transfer, than more requests to be made. You are not dependent to anyone, and as soon as your minified js is cached, you're super fast as well.
On first load, a CDN based solution might win, because you must load the additional jquery kilobytes from your own server (but, without an additional request). I doubt the difference is noticable, though. And then, on a first load with cleared cache, your own hosted solution will probably always be much faster, because of more requests (and DNS lookups) needed, to fetch the CDN jquery.
I wonder how this point is almost never mentioned, and how CDNs seem to take over the world :)