node.js TypeError: path must be absolute or specify root to res.sendFile [failed to parse JSON]

Question

[add] So my next problem is that when i try adding a new dependence (npm install --save socket.io). The JSON file is also valid. I get this error: Failed to parse json

Answer 1

in .mjs files we for now don't have __dirname

hence

res.sendFile('index.html', { root: '.' })