Understanding the 'fs.writeFileSync()' Method in Node.js

The 'fs.writeFileSync()' method in Node.js is a built-in function that allows you to write data to a file. This is done synchronously, unlike the 'fs.writeFile()' method which does the same operation asynchronously.

The synchronous nature of 'fs.writeFileSync()' means it will block the Node.js event loop until the file is written. This means that no other operations can be executed during that time. Hence, using this function can have an effect on performance, especially when writing large data or when this operation is performed frequently.

Let's understand this with an example. Consider you want to write "Hello, World!" to a file named 'example.txt'. The following code does that:

const fs = require('fs');

let data = 'Hello, World!';

// write data to a file with fs.writeFileSync()
fs.writeFileSync('example.txt', data);
console.log('File written successfully');

In the above code, we first include the Node.js File System module with require('fs'). Then, we define the data that we want to write to the file with let data = 'Hello, World!';. Afterwards, we call the 'fs.writeFileSync()' function with two parameters: the name of the file ('example.txt') and the data we want to write (data). Once the function has been successfully executed, Node.js will show 'File written successfully' in the console.

Even though 'fs.writeFileSync()' is extremely handy due to its simplicity, it’s best used sparingly and for small files. If your application frequently writes to files or if the files are large, 'fs.writeFileSync()' can slow down your application due to its blocking nature. In such cases, it's often a better idea to use its asynchronous counterpart: 'fs.writeFile()'.