Updating / Appending Files

To add new content instead of replacing it, you can use:

fs.appendFileSync()

This method adds data to the end of the file.

Example

const fs = require('fs');

fs.appendFileSync('notes.txt', '\nSecond note');

• \n creates a new line;
• The new note is added below the existing content.

Result in the File

First note
Second note

Each time you run this code, a new line will be added.

writeFileSync vs appendFileSync

It is important to understand the difference:

• writeFileSync: replaces all content;
• appendFileSync: adds new content.

Example Comparison

// Overwrites file
fs.writeFileSync('notes.txt', 'New content');

// Appends to file
fs.appendFileSync('notes.txt', '\nAnother note');

When to Use Appending

Appending is useful when you want to:

• Store multiple records (like notes or logs);
• Keep history of actions;
• Add new data without losing old data.