So I'm using Javascript and ajax to connect to a database through an php file, but something came in mind.
If a User log in, the user data will be stored in my Javascript file tittle UserProces.js as:
Var Username = "James"
Var Age ="25";
(Data obtain from a query through a php: RetrieveUserData.php)
If 1 minute after James loged in, another user name Amy log in will the values of name and age of amy will effect the values of James? Since there is only one UserProces.js.
Of course NO! Each user is getting his local copy of javascript file.
The server sends each client that requests the page a copy of the javascript file it has stored. That copy is then in their browser and running there. Any changes to variables are done in that copy in their browser. They have to way (well, unless you set up something special) to change the original file on the server. Think of it like this:
I'm a teacher with a test document on my computer (this is the javascript file on the server). For each student who comes into the class and asks to take the test (a client requesting the page) I'm going to print off a copy in my printer and give them. They will then write their name on the test and fill in answers (assign values to variables). A student doing this doesn't effect anyone else in the class because they aren't changing the original document, they are just editing their copy.
Not a perfect analogy, obviously, but pretty darn close.
Also, addressing a comment made earlier, you probably aren't accessing the service "through a php file". You are using a php file to generate a copy of the web page for the user to view. Again, printing off a copy for the user, but in this case the php file gives a special set of instructions for exactly what should be "printed off".
Each user will load the same script file but all variables, objects and everything else gets stored by each browser, and even your browser doesnt share that info, which prevents one website to have access to variables on another website.
So, final answer is no. They will not share any info. Just load the same "base".
Related
Can my JavaScript code be edited at runtime by (malicious) users, even when it is uploaded in a web hosting site?
For example if I declare a variable in my script something like:
var myvalue = 2;
I want to know if it can be edited to:
var myvalue = 1;
Short answer: yes.
Anyone can open the browser's Developer Tools and change values, execute arbitrary code, remove or change or edit anything they like.
So if there is anything crucial in your application where an invalid value could cause a security or data validation issue, then, if that data (or data which is derived using that value) is submitted to the server, it must be re-validated using server-side code (which of course cannot be changed) before being accepted.
P.S. Bear in mind that any edits to the code or variable values will only persist until the next time the page is re-loaded. When the page is refreshed, the JavaScript and HTML files will be downloaded again from the server and all code and variable values are reset to their starting state. Assuming there are no other security vulnerabilities in your server, then a malicious user cannot edit the original source code files which are stored there. They can only change the copy which gets loaded into the browser.
I am making a website where users make posts all the posts are stored in a variable i save these variables in local storage and i host the site through dropbox public folder.
Sadly you can only see your posts because there in local storage.
Is there a way i could store that variable in a json file so other users can access it?
E.g.
var dump = "User post 1"
user 2 can see user 1's post and when they submit a post
var dump = "User post 1, User post 2"
I already have it working with multiple posts but i want to be able to share them on multiple computers
maybe the vars value could be stored in a .json or .txt and when a user posts it adds to that file in dropbox?
JavaScript in the browser does not have the ability to write files, making this idea unfortunately an impossible one. Further complicating things, Dropbox (last I checked) only "serves" static pages, meaning you can't use JavaScript to do an HTTP POST to a Dropbox-hosted file.
Alas, I think the answer is, "No, it can't be done like this".
So I have this webpage that I'm making which allows people to create elements on the page on the fly. And I want to be able to save those elements to my server and whenever someone else reloads that page, the webpage will have those saved elements.
I'm not a good web programmer by any means, so take it easy with the web jargon xD
The user created elements are nested 's or lists. Those elements can be deleted at anytime as well.
So I was reading about saving them as JSON but how would I go about doing that as my 's, most of the top level ones will have the same class. Never worked with JSON before, so I'm a real noob at that.
Will the server file keep replacing itself with a brand new copy with each addition/deletion?
And I'd like to get a little help with showing the new elements without updating. On other users page. I read about AJAX real-time updating, like APE, but have no idea how to go about with that. (This is not really needed but would be a nice one to have)
If someone can guide me a little at least, that will be great. Thanks.
The best suitable way to accomplish this is by saving your objects attributes to a database, however other options include XML files etc..
The process of accomplishing it through database is:
If you want to save data to database then you will have to use a server side language like Php or Asp.net, so first step will be to have a database then an active connection to your database on your intermediate file (lets say 'data.php')
Then you need to code your data.php file so that it can take input(usually through GET or POST method) and it can save it to your database
Then you need to pass your data (objects attributes) through AJAX to data.php and save them to your database
On the main file you will have to check whether already some data exists for user, if yes then fetch it from database and display objects accordingly, otherwise set the objects preferences to default
Just a simple question, I was wondering why some websites have something like "?lang=EN" in their URL after selecting a language? Is it because their html file or folder containing it is named "?lang=EN", or some other code that does this? I'd like to set the URL like that for my website (has 2 languages). Currently I have folder structure like this:
Language selection: D:/media/index.html
EN site: D:/media/en/index.html
CN site: D:/media/cn/index.html
Files for the website: D:/media/site
Thanks.
First of all, anything after the file extension ( .html ) is a server side function.
The ? is a function for PHP and adds variables to the super global GET array ( in the form: ?variable=value&variable2=value2 ) that is directed to from another page and from that point many things can be done with the data.
Sites that use the ?lang=EN are probably programmed to print out the chunks of text needed on the single page in the places and languages required. Though it is possible using this method to redirect to a language specific directory.
Hope this helps :)
That's because they often have a content management system where the content isn't stored in files necessarily, but in a database. The lang=en is a GET variable from the URL that they retrieve in, for example, PHP, to display the correct content. In your case, however, you can just redirect the user if they click EN or CN to the appropriate locations, in your case, /en/index.html and /cn/index.html.
The url you see at the address bar, whatever comes after "?" is called "QueryString" and with libraries on the server side (based on the developing platform that website is made on) you can access the values. For instance the value of "lang" can be equal to "EN" or "CN" etc.
By the way you can have some http handlers to rewrite the requested url and get your parameters through the url that physically doesn't exists. Like the one you mentioned, "http://yoursite.com/en/default.whatever". I myself prefer this way but as you requested you should use some server side libraries to access the query string values and choose the language of the content you wanna send to client.
Also as one solution that once I used, you can also use some translation service (like translate.google.com) client libraries and call it at client side with jquery or even javascript and translate all the texts on page load. Although it's damn fast in action, it has some issues you will see.
Hope it helps.
PHP uses $_GET to get value from variables from the URL.It gets the value from that LANG variable and then it selects all from a file where are stored all the words in different languages or from the database
You don't need to copy every file and then translate it.
Search for php dynamic pages tutorial in your case. I found THIS.
P.S. PHP is one from many ways to do this.
On my homepage I have to set a cookie using the name of the logged in user. The cookie set and get part has to be done in JS. On the subsequent sub pages I have to retrieve the cookie(username) using the set variable name.
How can I store the username/cookie name so that it is publicly accessible across all the pages? This username will obviously change with each new user and is not constant.
I have tried doing this using external JS file but in every new page the value is reset to default which I don't want.
The exact solution to my problem is like the work done by:
public static variable
in Java (not final). I want to achieve this in JS.
There is no such thing in Javascript unless you use a storage API (client side storage, or cookies, or something like that). The reason is that when you move from one page to another, it doesn't particularly matter to the browser. It wipes its slate and starts over, keeping explicitly stored data like cookies and such, and deleting everything else that is dynamically created. So the short of it is, if you want each page to know the name, you have to include the name in each page's code (manually or via script).
I don't quite know your application. In javascript you have function prototypes. In a function prototype you can declare 'static' members like so:
function C(params for constructor){
C.aStaticVariable = 5;
}
alert(C.aStaticVariable); //available everywhere