Troubleshooting JSON parsing issue in Node.js Discord bot

Other Questions Discord bot
1

I’m trying to create a Discord bot using Node.js and the Discord API. But I’m running into a JSON parsing error when I start the bot. Here’s what I’m seeing:

SyntaxError: Unexpected end of JSON input
at JSON.parse (<anonymous>)

I think the problem might be in these lines:

let userData = JSON.parse(fs.readFileSync('Storage/userData.json', 'utf8'));

fs.writeFile('Storage/userData.json', JSON.stringify(userData), (err) => {
  if (err) console.error(err);
})

My bot is supposed to handle user data and money. It creates a JSON file for each user and guild if one doesn’t exist. But something’s not working right with reading or writing the JSON file.

I’ve double-checked my folder structure and the file paths seem correct. What could be causing this error? How can I fix it so my bot starts up properly?

Any help would be great. Thanks!

2

hey mandy, had similar issues b4. try wrapping ur JSON.parse in a try-catch block. if it fails, initialize userData as an empty object {}. also, make sure the file isn’t empty when u first create it. maybe add some default data. hope this helps!

3

I’ve faced similar JSON parsing issues in my Discord bot projects. One thing that helped me was implementing a file check before reading. You could try something like this:

const fs = require(‘fs’);
const filePath = ‘Storage/userData.json’;

let userData = {};
if (fs.existsSync(filePath)) {
const fileContent = fs.readFileSync(filePath, ‘utf8’);
if (fileContent) {
userData = JSON.parse(fileContent);
}
}

This approach ensures you only try parsing when the file exists and has content, avoiding unexpected errors on startup. Additionally, consider using async file operations using fs.promises for better performance in a production environment. This method has saved me quite a few headaches in the past.

4

The error you’re encountering suggests that the JSON file you’re trying to parse is empty or malformed. This can happen if the file doesn’t exist yet or if it was corrupted during a previous write operation.

To resolve this, you could implement a try-catch block when reading the file. If the file doesn’t exist or is empty, initialize userData with an empty object. Here’s how you might modify your code:

let userData;
try {
  userData = JSON.parse(fs.readFileSync('Storage/userData.json', 'utf8'));
} catch (error) {
  userData = {};
}

// Rest of your code...

This approach ensures that even if the file is missing or empty, your bot won’t crash on startup. It’s also a good practice to handle potential write errors more robustly, perhaps by logging them or notifying an admin if the write operation fails repeatedly.