Can javascript be used to write to a file?

Can javascript be used to wri开发者_StackOverflow社区te to a file ? Sorry restate that (Can javascript be used to write to a file on the web server it is hosted on? ).

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They used to call cookies "really small files on your computer", so I say: "Yes, yes it can."

update based on edit

Yes, you have to use AJAX to call a web service on the web server.

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It can if the "file" is a cookie. I will leave research on that up to the reader.

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Not cross-compatibly, unless you do certain trickery. A trusted applet, for example, has complete access to the user's file system, and it can expose javascript methods. Expose a write method in a trusted applet, and you're good to go.

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No. if you need to store data on the client, you can use cookies, Google Gears, or the client-side storage supported by modern browsers like firefox and safari.

The YUI Storage Utility is a nice cross-browser wrapper around these methods.

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On it's own, no.. at least without exploiting browser / plugin vulnerabilities.

Since you clarified your question:

It can be used to do an ajax call to a server-side script which would then write a file into the file system.

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You could make an Ajax call to a web service which would either save the file for you on the server or perhaps serve it back to the browser for download

using jQuery

$.ajax({
   type: "POST",
   url: "save.php",
   data: "name=Bob&Age=1",
   success: function(msg){
     alert( "Data Saved: " + msg );
   }
 });

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Unless used in server-side contexts: no, sorry.

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Javascript cannot directly write to a file on the webserver on which it is hosted. If it is required, you can use something like an XMLHttpRequest object to communicate your means to a serverside script (like PHP or Python), which will then do the write.

Javascript code is executed on the client side. It does not directly have access to your server.

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It depends on a platform. Some platforms (like Windows), allow javascript to access filesystem (in Windows - via FileSystemObject ActiveX object). But client's browser security settings must be adjusted to allow this.