{"id":88,"date":"2019-09-24T07:18:12","date_gmt":"2019-09-24T07:18:12","guid":{"rendered":"https:\/\/www.kindsonthegenius.com\/nodejs\/?p=88"},"modified":"2020-08-06T09:56:47","modified_gmt":"2020-08-06T09:56:47","slug":"node-js-file-system","status":"publish","type":"post","link":"https:\/\/www.kindsonthegenius.com\/nodejs\/node-js-file-system\/","title":{"rendered":"Node.js – File System"},"content":{"rendered":"

In previous Tutorials, we discussed Buffers<\/a>, then Streams<\/a>. File system is related as well.<\/p>\n

File System allows you to read and write data to file in your OS. This is made possible by the Node File System module(fs).<\/p>\n

We would examine the following sub-topics:<\/p>\n

    \n
  1. Asynchronous vs Synchronous Operation<\/a><\/li>\n
  2. Opening a File<\/a><\/li>\n
  3. Getting File Information<\/a><\/li>\n
  4. Writing to a File<\/a><\/li>\n
  5. Reading a File<\/a><\/li>\n
  6. Closing a File<\/a><\/li>\n
  7. Truncating a File<\/a><\/li>\n
  8. Deleting a File<\/a><\/li>\n
  9. Creating a Directory<\/a><\/li>\n<\/ol>\n

     <\/p>\n

    1. Synchronous vs Asynchronous Operations<\/strong><\/p>\n

    the fs module provides methods that both synchronous and asynchronous forms.<\/p>\n

    For example, we learnt of readFile() and readFileSync() when we learn of callbacks<\/a>. The readFile() is the asynchronous equivalent of readFileSync().<\/p>\n

    Asynchronous methods take callback functions as the last parameter. There are many benefits of using asynchronous method. It provides for better performance since it does not tie down the thread.<\/p>\n

    The code below reads data asynchronously from a file named testoutput.txt.<\/p>\n

    \/\/Demonstrating Async and Sync operations<\/span>\r\nvar<\/span> fs =<\/span> require(\"fs\"<\/span>);\r\n\r\n\/\/Read file Asynchronously<\/span>\r\nfs.readFile('D:\/nodefiles\/testinput.txt'<\/span>, function<\/span> (err, data) {\r\n   if<\/span> (err) {\r\n      return<\/span> console.error(err);\r\n   }\r\n   console.log(\"Reading Asynchronously: \"<\/span> +<\/span> data.toString());\r\n});\r\n\r\n\/\/Reading Synchronously<\/span>\r\nvar<\/span> data =<\/span> fs.readFileSync('D:\/nodefiles\/testinput.txt'<\/span>);\r\nconsole.log(\"Reading Synchronously: \"<\/span> +<\/span> data.toString());\r\n\r\nconsole.log(\"End of Program\"<\/span>);\r\n<\/pre>\n
     <\/p>\n
    2. Opening a File<\/strong><\/p>\n
    You can open a file in your computer using the syntax below.<\/p>\n
    fs.open(path, flags[, mode], callback)\r\n<\/pre>\n
    Where<\/p>\n