Why does fs.writeFile fail to create and write data?

I am trying to write a JSON file and for some reason fs.writeFile just won’t create and write the string in the file. The function described is being called by an HTML button :

<button type="button" onclick="writeJson ();">Write</button>

I press the button and nothing happens. I had error/success outputs in the function, but took them out in case they were causing the function to fail.
I am 99% sure it’s my syntax causing it, but I can’t seem to see where.

function writeJson () {
const fs = require('node:fs');
const stri= "test";
fs.writeFile('Test.json', stri, err => {
  if (err) {
   
  } else {
    
  }
});
}