Reading JSON files in Node.js

JSON is the most popular format for swapping and saving data in web applications. It is easily readable and writable. Therefore, it is widely used amongst developers for different use cases.

In Node.js, in most cases, you work with JSON files on back-end development when you can save structured data or your configurations to JSON. 

In this article, let’s see some different approaches to us Node.js to read JSON files and show real-world use cases to help you use JSON data easily in your applications.

Why Do We Need to Read JSON Files in Node.js?

These are some of the top reasons why you should use Node.js to read JSON file

1. API Simulation and Testing: Developers often require JSON files to simulate an API response in development or for just plain mocking of data for the backend.
   
2. Product and Configuration Data: JSON is a standard way of storing product details, configuration settings in an application, which can be read or at the same time easily manipulated.
   
3. Data Exchange: JSON as a format has become the standard in data exchange between client and server on most web applications. When it comes to working with different data sources, the interaction between server-side code and JSON files happens seamlessly.

Methods to Read JSON Files in Node.js

Let’s see the top 2 commonly used approaches to read JSON Files in Node.js

Method 1: Using require()

This method makes it easy to import a JSON file as a module to your JavaScript code. The require() function automatically parses the JSON data. So this makes it available as a JavaScript object.

Steps:

1. Create a new folder.
   
2. Create a JSON file in that folder.
   
3. Lastly, to read the JSON information, write a JavaScript file.

JSON File:

A JSON file has a key and value pair in which the unique keys are present in JSON

JS File:

• The first line requires (‘/.data/json’). It refers to the path of a JSON file where it’s located in a folder 
• Then we use console.log, which helps to display values from json file 
• The (data.name, data.role) indicates the key used in the file (JSON).

Output: 

Explanation: 

• In JS file, `data.name` denotes the key `name` stored in the JSON file. And the key `name` contains the value `John`. So now `data.name` will return “John” as a result.

• It’s important to note that JSON keys are case-sensitive. For example, if you use `”Name”` instead of `”name”`, it will return `undefined` or `null` because the key in the JSON file is lowercase (`name`). To get the right value, you must use the exact key name as it appears in the JSON file.

Method 2: Using fs.readFile()

The fs.readFile() method allows you to read a JSON file’s contents asynchronously. This technique will be helpful for big file management or other asynchronous operations.

Steps:

1. Create a new folder.
   
2. Create a JSON file in the folder.
   
3. To read the JSON file, create a JS file.
   

JS File:

Explanation:

• The readFile() reads the whole file and writes it into the JSON string variable. Now we have a copy of json file. But we have to parse the file into JSON format by using the parse function
• We use the try and catch method to handle any issue, like wrong file path or a file having different data. If a problem is found, the user will be notified of the error.
• Try and catch help to prevent unexpected errors so that the code execution will not be stopped. 

Output: 

Use Cases for JSON in Node.js

1. A JSON file is used for API testing to check its working or not 
2. In database, we use the JSON type format to store a specific type of data
3. JSON format is used in package.json and the config file for structured format 
4. JSON file is a key-value pair. So, the duplicate data is avoided
   

Conclusion

It’s normal practice to read JSON files in Node.js. It can be used if you’re simulating API data during development, handling product data, or working with configuration files. 

Using the require() function or the fs.readFile() method allows developers to easily interact with JSON data, with the latter being more suitable for handling large or asynchronous data. 

Understanding these methods and their use cases can significantly improve a developer’s ability to work with structured data and integrate JSON effectively into Node.js applications.