fs.writeFileSync function doesn't write to file when included as a module - node.js

Question

Consider the following:
conversations.json : []
db.js :
let fs = require('fs');
let conversations = require('./conversations.json');
function addConversation(conversation){
console.log(conversations);
conversations.push(conversation);
try{
fs.writeFileSync('conversations.json', JSON.stringify(conversations));
}
catch(err){
console.error('Parse/WriteFile Error', err)
}
}
module.exports = {
addConversation
}
app.js :
let database = require('./db.js');
database.addConversation(
{
key1: '1233',
key2: '433',
key3: '33211'
}
);
Running:
node app.js
No error is being raised. Everything compiled as expected. The problem is that the conversations.json isn't being updated once the addConversation function is called from app.js.
What's interesting is that once the addConversation is called within the db.js everything works great and the conversations.json is being updated.
What am I missing?

Answer 1

What am I missing?
Probably when loading as a module, you're writing the file to the wrong directory.
When you do this:
fs.writeFileSync('conversations.json', JSON.stringify(conversations));
That writes conversations.json to the current working directory which may or may not be your module directory. If you want it written to your module directory which is where this:
let conversations = require('./conversations.json');
will read it from, then you need to use __dirname to manufacture the appropriate path.
fs.writeFileSync(path.join(__dirname, 'conversations.json'), JSON.stringify(conversations));
require() automatically looks in the current module's directory when you use ./filename, but fs.writeFileSync() uses the current working directory, not your module's directory.