I know it's impossible to hide source code but, for example, if I have to link a JavaScript file from my CDN to a web page and I don't want the people to know the location and/or content of this script, is this possible?
For example, to link a script from a website, we use:
<script type="text/javascript" src="http://somedomain.example/scriptxyz.js">
</script>
Now, is possible to hide from the user where the script comes from, or hide the script content and still use it on a web page?
For example, by saving it in my private CDN that needs password to access files, would that work? If not, what would work to get what I want?
Good question with a simple answer: you can't!
JavaScript is a client-side programming language, therefore it works on the client's machine, so you can't actually hide anything from the client.
Obfuscating your code is a good solution, but it's not enough, because, although it is hard, someone could decipher your code and "steal" your script.
There are a few ways of making your code hard to be stolen, but as I said nothing is bullet-proof.
Off the top of my head, one idea is to restrict access to your external js files from outside the page you embed your code in. In that case, if you have
<script type="text/javascript" src="myJs.js"></script>
and someone tries to access the myJs.js file in browser, he shouldn't be granted any access to the script source.
For example, if your page is written in PHP, you can include the script via the include function and let the script decide if it's safe" to return it's source.
In this example, you'll need the external "js" (written in PHP) file myJs.php:
<?php
$URL = $_SERVER['SERVER_NAME'].$_SERVER['REQUEST_URI'];
if ($URL != "my-domain.example/my-page.php")
die("/\*sry, no acces rights\*/");
?>
// your obfuscated script goes here
that would be included in your main page my-page.php:
<script type="text/javascript">
<?php include "myJs.php"; ?>;
</script>
This way, only the browser could see the js file contents.
Another interesting idea is that at the end of your script, you delete the contents of your dom script element, so that after the browser evaluates your code, the code disappears:
<script id="erasable" type="text/javascript">
//your code goes here
document.getElementById('erasable').innerHTML = "";
</script>
These are all just simple hacks that cannot, and I can't stress this enough: cannot, fully protect your js code, but they can sure piss off someone who is trying to "steal" your code.
Update:
I recently came across a very interesting article written by Patrick Weid on how to hide your js code, and he reveals a different approach: you can encode your source code into an image! Sure, that's not bullet proof either, but it's another fence that you could build around your code.
The idea behind this approach is that most browsers can use the canvas element to do pixel manipulation on images. And since the canvas pixel is represented by 4 values (rgba), each pixel can have a value in the range of 0-255. That means that you can store a character (actual it's ascii code) in every pixel. The rest of the encoding/decoding is trivial.
The only thing you can do is obfuscate your code to make it more difficult to read. No matter what you do, if you want the javascript to execute in their browser they'll have to have the code.
Just off the top of my head, you could do something like this (if you can create server-side scripts, which it sounds like you can):
Instead of loading the script like normal, send an AJAX request to a PHP page (it could be anything; I just use it myself). Have the PHP locate the file (maybe on a non-public part of the server), open it with file_get_contents, and return (read: echo) the contents as a string.
When this string returns to the JavaScript, have it create a new script tag, populate its innerHTML with the code you just received, and attach the tag to the page. (You might have trouble with this; innerHTML may not be what you need, but you can experiment.)
If you do this a lot, you might even want to set up a PHP page that accepts a GET variable with the script's name, so that you can dynamically grab different scripts using the same PHP. (Maybe you could use POST instead, to make it just a little harder for other people to see what you're doing. I don't know.)
EDIT: I thought you were only trying to hide the location of the script. This obviously wouldn't help much if you're trying to hide the script itself.
Google Closure Compiler, YUI compressor, Minify, /Packer/... etc, are options for compressing/obfuscating your JS codes. But none of them can help you from hiding your code from the users.
Anyone with decent knowledge can easily decode/de-obfuscate your code using tools like JS Beautifier. You name it.
So the answer is, you can always make your code harder to read/decode, but for sure there is no way to hide.
Forget it, this is not doable.
No matter what you try it will not work. All a user needs to do to discover your code and it's location is to look in the net tab in firebug or use fiddler to see what requests are being made.
From my knowledge, this is not possible.
Your browser has to have access to JS files to be able to execute them. If the browser has access, then browser's user also has access.
If you password protect your JS files, then the browser won't be able to access them, defeating the purpose of having JS in the first place.
I think the only way is to put required data on the server and allow only logged-in user to access the data as required (you can also make some calculations server side). This wont protect your javascript code but make it unoperatable without the server side code
I agree with everyone else here: With JS on the client, the cat is out of the bag and there is nothing completely foolproof that can be done.
Having said that; in some cases I do this to put some hurdles in the way of those who want to take a look at the code. This is how the algorithm works (roughly)
The server creates 3 hashed and salted values. One for the current timestamp, and the other two for each of the next 2 seconds. These values are sent over to the client via Ajax to the client as a comma delimited string; from my PHP module. In some cases, I think you can hard-bake these values into a script section of HTML when the page is formed, and delete that script tag once the use of the hashes is over The server is CORS protected and does all the usual SERVER_NAME etc check (which is not much of a protection but at least provides some modicum of resistance to script kiddies).
Also it would be nice, if the the server checks if there was indeed an authenticated user's client doing this
The client then sends the same 3 hashed values back to the server thru an ajax call to fetch the actual JS that I need. The server checks the hashes against the current time stamp there... The three values ensure that the data is being sent within the 3 second window to account for latency between the browser and the server
The server needs to be convinced that one of the hashes is
matched correctly; and if so it would send over the crucial JS back
to the client. This is a simple, crude "One time use Password"
without the need for any database at the back end.
This means, that any hacker has only the 3 second window period since the generation of the first set of hashes to get to the actual JS code.
The entire client code can be inside an IIFE function so some of the variables inside the client are even more harder to read from the Inspector console
This is not any deep solution: A determined hacker can register, get an account and then ask the server to generate the first three hashes; by doing tricks to go around Ajax and CORS; and then make the client perform the second call to get to the actual code -- but it is a reasonable amount of work.
Moreover, if the Salt used by the server is based on the login credentials; the server may be able to detect who is that user who tried to retreive the sensitive JS (The server needs to do some more additional work regarding the behaviour of the user AFTER the sensitive JS was retreived, and block the person if the person, say for example, did not do some other activity which was expected)
An old, crude version of this was done for a hackathon here: http://planwithin.com/demo/tadr.html That wil not work in case the server detects too much latency, and it goes beyond the 3 second window period
As I said in the comment I left on gion_13 answer before (please read), you really can't. Not with javascript.
If you don't want the code to be available client-side (= stealable without great efforts),
my suggestion would be to make use of PHP (ASP,Python,Perl,Ruby,JSP + Java-Servlets) that is processed server-side and only the results of the computation/code execution are served to the user. Or, if you prefer, even Flash or a Java-Applet that let client-side computation/code execution but are compiled and thus harder to reverse-engine (not impossible thus).
Just my 2 cents.
You can also set up a mime type for application/JavaScript to run as PHP, .NET, Java, or whatever language you're using. I've done this for dynamic CSS files in the past.
I know that this is the wrong time to be answering this question but i just thought of something
i know it might be stressful but atleast it might still work
Now the trick is to create a lot of server side encoding scripts, they have to be decodable(for example a script that replaces all vowels with numbers and add the letter 'a' to every consonant so that the word 'bat' becomes ba1ta) then create a script that will randomize between the encoding scripts and create a cookie with the name of the encoding script being used (quick tip: try not to use the actual name of the encoding script for the cookie for example if our cookie is name 'encoding_script_being_used' and the randomizing script chooses an encoding script named MD10 try not to use MD10 as the value of the cookie but 'encoding_script4567656' just to prevent guessing) then after the cookie has been created another script will check for the cookie named 'encoding_script_being_used' and get the value, then it will determine what encoding script is being used.
Now the reason for randomizing between the encoding scripts was that the server side language will randomize which script to use to decode your javascript.js and then create a session or cookie to know which encoding scripts was used
then the server side language will also encode your javascript .js and put it as a cookie
so now let me summarize with an example
PHP randomizes between a list of encoding scripts and encrypts javascript.js then it create a cookie telling the client side language which encoding script was used then client side language decodes the javascript.js cookie(which is obviously encoded)
so people can't steal your code
but i would not advise this because
it is a long process
It is too stressful
use nwjs i think helpful it can compile to bin then you can use it to make win,mac and linux application
This method partially works if you do not want to expose the most sensible part of your algorithm.
Create WebAssembly modules (.wasm), import them, and expose only your JS, etc... workflow. In this way the algorithm is protected since it is extremely difficult to revert assembly code into a more human readable format.
After having produced the wasm module and imported correclty, you can use your code as you normallt do:
<body id="wasm-example">
<script type="module">
import init from "./pkg/glue_code.js";
init().then(() => {
console.log("WASM Loaded");
});
</script>
</body>
I have a website that loads mostly using AJAX calls. The javascript and CSS files are only loaded once when the page first loads.
My issue is that the javascript/CSS can get out of sync with the HTML and server-side code. The page can be using an old versions of the javascript file (from when the page first loaded) while the server-side code and ajax-loaded HTML files always use the latest code and files.
What are some strategies for dealing with this?
I have considered polling the server at set intervals and asking if there is a newer version of the JS. Then, if there is, reloading the page. But, it seems that this can get ugly, with the page suddenly reloading at awkward moments instead of, for example, as the result of a user-initiated call.
Also, there are some changes to the javascript that do not necessarily require that a page be reloaded. For example, the changes might affect a different page/module than the one that the user is on.
Re-loading the javascript with every Ajax call is not viable
I can imagine ugly solutions to this, but thought I'd ask first.
EDIT (in response to comments and suggested answers)
The only way to get the JS back into sync is to reload the page, which then loads the new JS. Adding new JS to an old page won't work as it doesn't get rid of any old functions, listeners, etc. I'm not asking how to reload a page or how to load javascript. I'm asking for a strategy of knowing WHEN to do it, especially in a way that does not seem awkward to the user. Do people incorporate polling to ask if there is a new JS version? Do they then suddenly (from the user's point of view) reload the page? Do they poll even when the tab is hidden? Is this a problem for the server? Where do they keep track of the latest required JS version? Or, do they ask with every AJAX request - hey, should I reload? Did they write a special function for that? Do they keep all new html/server code backwards compatible with the js?
Someone who has dealt with this, how do you do it?
Two possible solutions include
calling $.getScript() to retrieve, update variables at document from at server-side to match variables at document before calling $.ajax(/* settings */) ;
alternatively could use web workers to update original document variables to match server-side variables at beforeSend of $.ajax(/* settings */)
At result of first step of either approach, abort $.ajax() call, call error handlers, notify user, send message to server about error.
var head = document.getElementsByTagName("head")[0],
scripts = {};
function load_script(name){
var myscript = document.createElement('script');
myscript.setAttribute("type","text/javascript");
myscript.setAttribute("src", name);
if (scripts[name]) head.replaceChild(myscript, scripts[name]);
else head.appendChild(myscript);
scripts[name] = myscript;
}
// the first call to load the script code
// and then call if you decide to upgrade a newer version
load_script('js1.js');
load_script('js2.js');
we have a code that makes some stuff:
$(function(){
//websocket connection
//ajax requests
//other stuff
});
if the code was loaded the browser has compiled it, so can the user change this code and reload the page with the altered code?
because function that are inside this anonymous jquery function can't be executed in the browser console, thus they are not accessable, the question is: are there any posibilities to hack this type of code?
A user could just copy the anonymous function, including the code inside, to his console, and run it.
Basically, any and all code you send to the client can be accessed, modified, and run.
Validate anything that needs to be validated, server-side. Use client-side validation only to make your application "prettier".
It can be easily copy to console in Google Chrome for example, changed and fired from there. And user can easily see this script for example in Sources tab. So yes, it's possible.
So if it's function that user cannot see I reccomend not to use Javascript or any script language on the client side.
I don't know what is your issue in particular, but a couple of recommendations.
Never trust the user, nor anything that comes from the client. It can be easily manipulated. ALWAYS check the data server side. Check that the fields are the correct type, especially in languages like PHP, never use the entire POST data, always filter it.
Minify your code and use closure this way you reduce the change the user can mess with your code
Give access to user only to the parts that are his responsibility, this way if he messes with your code only he is damaged.
Use secure cookies and https if you can. Check CSRF and XSS, and use ways to be safe of this.
You can't avoid that the user will do as he pleases, but you can make so he can only touch his data
I'm doing some code that requires actions on multiple sites (get some data switch to another site etc.) in a loop.
I'm trying to do this using setInterval().
Simplified, the task looks like this when launched in a console:
function checkit() {
window.location='http://www.google.pl';
}
var nre = setInterval(checkit,5000);
I have tried launching this script (in more complicated forms through different measures, from bookmarklet, from server side script etc, the interval runs OK in my original code, even does everything what I require in a loop until another page is called (through window.open or window.location). than the loop just seizes to execute.
I'm pretty new to JS (2 days experience) so I'm probbably doing something uterly stupid. Any Advice on how to get this thing going (is this even possible)?
Best regards
The problem you're going to have is that JS doesn't stay from page to page, so once the page changes, that loop goes away. You'll need to have the JS on each page you're wanting to visit to continue flow and even then, the variables are nuked when you change pages.
The only way to circumvent this issue is by storing a serialized object (or JSON string) within the window.name value which is remember across pages and domains within that tab.
I have a ASP.Net Repeater control with a Table inside it. Is it possible to run a JavaScript function directly AFTER I call MyRepeater.DataBind()? I've been trying different things, but nothing is triggering the JavaScript function.
Thanks
Databinding occurs on the server in a postback as part of the Page Lifecycle process. In other words, excluding partial-postbadks, at the time this happens any existing DOM in the browser is destroyed. A whole new page is constructed on the server and transmitted to the browser, so that a new DOM can be built and rendered.
What all that means is that you want to think in terms of running your javascript in the page's onload event. One way to make this happen is using the ClientScriptManager.
Javascript can be called from server side by using RegisterStartupScript and RegisterClientScriptBlock methods.
http://www.mindfiresolutions.com/Register-clientside-startup-script-from-serverside-code-286.php
No. The javascript isn't even going to render and run until the code-behind has executed and the page delivered to the client. So it won't matter if adding the script is the first thing you do in the code-behind or the last thing you do (or directly after the DataBind()).
When using the ClientScriptManager Class, look at your code behind and you'll see the dynamic javascript is added just before the ending </form> tag (although it still may be possible to accomplish what you want to do, just with a different approach).
Well I found a solution, not sure it's the cleanest way to do it, but for my application's context it works:
I ran the javascript code after a partial postback using: Sys.WebForms.PageRequestManager.getInstance().add_endRequest();
Again, not the cleanest but suits the needs I have.
Thanks for all your input