Let me explain something further about the code we discussed in our last episode.

fs.readFileSync("./file.txt", "utf8");

This function reads the contents of a file synchronously, meaning it will actually block the main thread while it’s running.

What does this mean?

• The V8 engine is responsible for executing JavaScript code, but it cannot offload this task to Libuv (which handles asynchronous operations like I/O tasks).
• Think of it like an ice cream shop where the owner insists on serving each customer one at a time, without moving on to the next until the current customer has been fully served. This is what happens when you use synchronous methods like fs.readFileSync()—the main thread is blocked until the file is completely read

Why is this important?

• As a developer, it’s important to understand that while Node.js and the V8 engine give you the capability to block the main thread using synchronous methods, this is generally not recommended.
• Synchronous methods like fs.readFileSync() are still available in Node.js, but using them can cause performance issues because the code execution will be halted at that point (e.g., line 7) until the file reading operation is complete.

Best Practice

• Avoid using synchronous methods in production code whenever possible, especially in performance-critical applications, because they can slow down your application by blocking the event loop.
• Instead, use asynchronous methods like fs.readFile() that allow other operations to continue while the file is being read, keeping the application responsive.

Let me show you another example of blocking code in Node.js.

Introducing the crypto Module