Node script ReferenceError: fs is not defined error in test script

I am trying out node to run a simple js script to read a file, following is the content of my script:

"use strict"
fs = require('fs');
var args = process.argv.slice(2);
fs.readFile(args, 'utf8', function (err,data) {
  if (err) {
      return console.log(err);
        }
    console.log("Reading from file " + args);
    console.log(data);
});

when I try to run this using the following command: node myTestFile.js testFile

I get this error:

fs = require('fs');
   ^
ReferenceError: fs is not defined
    at Object.<anonymous>     (/<Path to file>/myTestFile.js:2:4)
at Module._compile (module.js:570:32)
at Object.Module._extensions..js (module.js:579:10)
at Module.load (module.js:487:32)
at tryModuleLoad (module.js:446:12)
at Function.Module._load (module.js:438:3)
at Module.runMain (module.js:604:10)
at run (bootstrap_node.js:393:7)
at startup (bootstrap_node.js:150:9)
at bootstrap_node.js:508:3

Isn't fs in node like a library like stdio in c ?

Do we have to explicitly define the library path somewhere in node ?

How can I get the above example to work ?

via Dhairya Seth