Reading Text Files in JavaScript Using Node.js

Welcome to the first lesson in our course on "Fundamentals of Text Data Manipulation." This lesson will introduce you to the essential skill of reading text files using JavaScript, specifically with Node.js. Text files are a vital data source in programming, commonly used for storing data, configuration files, and logs. Being able to open and read files in JavaScript is a foundational skill you'll often rely on when working with data. By the end of this lesson, you will be able to read the entire contents of a text file into a string, an essential skill for various data manipulation tasks. Let's get started!

A file path is essentially the address of a file in your system's storage. It tells your program where to find or save a file. There are two types of file paths:

• Absolute Path: This is the full path to a file, starting from the root directory. Here are some examples from different operating systems:

  • Linux: /home/user/documents/input.txt
  • Mac: /Users/user/documents/input.txt
  • Windows: C:\\Users\\user\\documents\\input.txt

• Relative Path: This path is relative to the directory from which the script is executed. For example, documents/input.txt assumes your script is running from the user directory in the examples above.

Here's how you can specify a file path in JavaScript using Node.js:

const filePath = 'input.txt';  // Relative path

Make sure your Node.js script and the text file are in the same directory if you use a relative path. Otherwise, use the absolute path to ensure that Node.js can find your file.

When working with relative paths, it's important to understand the structure of your directories. Here are a few examples with file trees:

1. Example 1:

   File Tree:

   text

   project/
   ├── script.js
   └── data/
       └── input.txt

   Relative Path:

   JavaScript

   const filePath = 'data/input.txt';

2. Example 2:

   File Tree:

   text

   user/
   ├── documents/
   │   └── script.js
   └── input.txt

   Relative Path:

   JavaScript

   const filePath = '../input.txt';

   The .. is used to navigate to the parent directory. It works this way in both MacOS/Linux and Windows.

3. Example 3:

   File Tree:

   text

   application/
   ├── scripts/
   │   ├── script1.js
   │   └── script2.js
   └── resources/
       └── input.txt

   Relative Path (assuming the script is in script2.js):

   JavaScript

   const filePath = '../resources/input.txt';

These examples illustrate how relative paths depend on the current working directory of your script.