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

Question

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 ?

Answer 1

The problem is not require('fs'), but the left side; you'd get the same error with

fs = 42;

That's because there is no variable fs defined. Define it with const, let, or var, like this:

const fs = require('fs');

Answer 2

As mentioned in the log

ReferenceError: fs is not defined

You have a ReferenceError you can define the JS

const fs = require('fs');

or

var fs = require('fs');

and declare the fs before using it.

const or var depend on the javascript syntax you are using to build your application

Answer 3

// Define the `fs` at the beginning of the script
const fs = require('fs');