Question: Can anybody give some sample code to read and write a file using JavaScript?

Answer: 
here's the mozilla proposal

<http://www-archive.mozilla.org/js/js-file-object.html>

this is implemented with a compilation switch in spidermonkey, and also in adobe's extendscript. Additionally (I think) you get the File object in firefox extensions.

rhino has a (rather rudementary) readFile function
<https://developer.mozilla.org/en/Rhino_Shell>

for more complex file operations in rhino, you can use java.io.File methods.

you won't get any of this stuff in the browser though. For similar functionality in a browser you can use the SQL database functions from HTML5, clientside persistence, cookies, and flash storage objects.
To create file try

```
function makefile(){
  var fso;
  var thefile;

    fso = new ActiveXObject("Scripting.FileSystemObject");
    thefile=fso.CreateTextFile("C:\\tmp\\MyFile.txt",true);

    thefile.close()
    }

```

Create your directory in the C drive because windows has security against writing from web
e.g create folder named "tmp" in C drive.