LAB 1 - creating file using node.js fs module

LAB 1 #opensource

Creating file using node.js fs module:

If we want to work with file system in node, we will need to learn how to create files. In this blog post I will describe how to create and open files in node.js using the "fs" module.

Here are the steps to do it:

1. var fs = require('fs');
   Include a module to your code.
2. There are couple of methods to create a file:

• fs.writeFile("<fileName>",<content>,<callbackFunction>);
  In this case a new file is created with the provided name. After filling the file with content, callback function is called. If a file already exists , the file gets overwritten with a new file.
• fs.appendFile("<fileName>",<content>,<callbackFunction>);
  This function appends content to the file. After filling the file with content, callback function is called. If the file does not exist, a new file is created with the name and content provided.

Opening a file using node.js fs module:

• fs.open("<fileName>",<mode>,<callbackFunction>);
  This function opens to the file in the specified mode. If the file does not exist the new file is created with specified name.

List of modes:

table from: https://www.tutorialspoint.com/nodejs/nodejs_file_system.htm

Code examples:

var fs = require('fs'); 

fs.writeFile('lab1.txt', 'creating the file in node.js', function (err) { 

  if (err) 

     throw err; 

  console.log('Success!'); 

}); 

fs.appendFile('lab1.txt', 'new content', function (err) { 

  if (err) 

     throw err; 

  console.log('Success!'); 

}); 

fs.open('lab1.txt', 'rs', function (err, file) { 

   if (err) 

     throw err; 

  console.log('File is opened in "synchronous reading" mode'); 

});

Sources:

https://nodejs.org/api/fs.html

https://www.tutorialspoint.com/nodejs/nodejs_file_system.htm