const fs = require("fs");

let srtData = fs.readFileSync("sub.srt", "UTF-8");
let pattern = /[.](?=[0-9])/g;

let formattedSRT = srtData.replace(pattern, ",");

fs.writeFile("subReplace.srt", formattedSRT, err => {
  if (err) {
    return console.log(err);
  } else {
    console.log("File successfully created" + formattedSRT);
  }
});