I am currently using javascript and XMLHttpRequest on a static html page to create a view of a record in Zotero. This works nicely except for one thing: The page html title.
I can of course also change the <title>...</title> tag, but if someone wants to post the view to for example facebook the static title on the web page will be shown there.
I can't think of any way to fix this with just a static page with javascript. I believe I need a dynamically created page from a server that does something similar to XMLHttpRequest.
For PHP there is HTTPRequest. Now to the problem. In the javascript version I can use asynchronous calls. With PHP I think I need synchronous calls. Is that something to worry about?
Is there perhaps some other way to handle this that I am not aware of?
UPDATE: It looks like those trying to answer are not at all familiar with Zotero. I should have been more clear. Zotero is a reference db located at http://zotero.org/. It has an API that can be used through XMLHttpRequest (which is what I said above).
Now I can not use that in my scenario which I described above. So I want to call the Zotero server from my server instead. (Through PHP or something else.)
(If you are not familiar with the concepts it might be hard to understand and answer the question. Of course.)
UPDATE 2: For those interested in how Facebook scraps an URL you post there, please test here: https://developers.facebook.com/tools/debug
As you can see by testing there no javascript is run.
Sorry, im not sure if i understand what you are trying to ask, are you just wanting to change the pages title?
Why not use javascript?
document.title = newTitle
Facebook expects the title (or opengraph :title tags) to be present when it fetches the page. It won't execyte any JavaScript for you to fill in the blanks.
A cool workaround would be to detect the Facebook scraper with PHP by parsing the User Agent string, and serving a version of the page with the information already filled in by PHP instead of JavaScript.
As far as I know, the Facebook scraper uses this header for User Agent: "facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)"
You can check to see if part of that string is present in the header and load the page accordingly.
if (strpos($_SERVER['HTTP_USER_AGENT'], 'facebookexternalhit') !== false)
{
//synchronously load the title and opengraph tags here.
}
else
{
//load the page normally
}
Opening a site economizing the data load I seem to run into a need to add more data from Python occasionally. I use Python with CherryPy and Mako for loading a site.
So, how can I make a JavaScript request from Python to pass me some more data, once the site was loaded already. I want to do that without moving away from the site. I know that JavaScript can do all sorts of things, but Python can be a real muscle for me with better debugging features.
Now, I'm not keen on Ajax. I know nothing about it and I have that fear factor that it would be quite complex.
TIA
Dennis
For example you can make with jQuery like this,
in controller you return rendered template:
def some_html():
return render('my_template.tpl')
and in the client side you can use jQuery
<script type="text/javascript">
('#result_from_server').load('/some_html');
</script>
,where result_from_server its can be id of wrapper div like
<div id="result_from_server"></div>
and /some_html, url for call your some_html() function.
Very good resurce for quick start with jQuery jqapi.com
I have a script that sends emails (subscriptions). Processing takes long enough. The script outputs a log (of what is successfully sent to the moment) to browser.
I would like it to show progress bar also. How do I do that? There is no AJAX calls, page loads synchronously. I thought may be I should just output <script>...</script> tags every X email sendings to move progress bar, but I'm not sure it's cross-browser compliant. Is that a standard, that browser should execute Javascript as soon as it encounters some in the page body?
Yes, your idea is used very often and should work in most browsers - the standard is that javascript must be executed synchronously, unless specifically told not to by the async attribute.
So you can just put in a script tag every now and again to update the status bar. Gmail uses the same technique, as far as I know.
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>
Very simple Ajax request taking employee id and returning the user info as HTML dumb.
Request ajax("employee/info?emp_id=3543")
Response id = 3543name = some name
This is just another simple JS trick to populate the UI. However i do not understand how something like below is equally able to execute correctly and dump the HTML code.
<script type="text/javascript" src="employee/info?emp_id=3543" />
When page encounters following code it executes like the ajax request is executed and dumps code into page. Only difference is its no more asynchronous as in case of Ajax.
Questions :
Is this correct approach ? its +ves and -ves.
Which are the correct scenarious to user it?
Is this also means that any HTML tag taking "src" tag can be used like this?
I have used this kind of javascript loading for cross domain scripting. Where it is very useful. Here is an example to show what I mean.
[Keep in mind, that JS does not allow cross domain calls from javascript; due to inbuilt security restrictions]
On domain www.xyz.com there lies a service that give me a list of users which can be accessed from http://xyz.com/users/list?age=20
It returns a json, with a wrapping method like following
JSON:
{username:"user1", age:21}
If I request this json wrapped in a method like as follows:
callMyMethod({username:"user1", age:21})
Then this is a wrapped json which if loads on my page; will try to invoke a method called callMyMethod. This would be allowed in a <script src="source"> kind of declaration but would not be allowed otherwise.
So what I can do is as follows
<script language="javascript" src="http://xyz.com/users/list?age=20"></script>
<script language="javascript">
function callMyMethod(data)
{
//so something with the passed json as data variable.
}
</script>
This would allow me to stuff with JSON coming from other domain, which I wouldn't have been able to do otherwise. So; you see how I could achieve a cross domain scripting which would have been a tough nut to crack otherwise.
This is just one of the uses.
Other reasons why someone would do that is:
To version their JS files with
releases.
To uncache the js files so that they are loaded on client as soon as some changes happen to js and params being passed to URL will try to fetch the latest JS. This would enable new changes getting reflected on client immediatly.
When you want to generate conditional JS.
The usage you have specified in example wouldn't probably serve much purpose; would probably just delay the loading of page if processing by server takes time and instead a async ajax call would be much preferred.
Is this correct approach ? its +ves
and -ves.
Depends whether you want to use asynchronous (ajax) way or not. Nothing like +ve or -ve.
The later method takes more time though.
Which are the correct scenarious to
user it?
Ajax way is the correct method there in that sense.
Is this also means that any HTML tag
taking "src" tag can be used like
this?
src is used to specify the source path. That is what it is meant to do.