Convert Google speech to text JSON into SRT

index.js

const text = require("./text.json");

function toHHMMSS(seconds) {
  var sec_num = parseInt(seconds, 10); // don't forget the second param
  var hours = Math.floor(sec_num / 3600);
  var minutes = Math.floor((sec_num - hours * 3600) / 60);
  var seconds = sec_num - hours * 3600 - minutes * 60;

  if (hours < 10) {
    hours = "0" + hours;
  }
  if (minutes < 10) {
    minutes = "0" + minutes;
  }
  if (seconds < 10) {
    seconds = "0" + seconds;
  }
  return hours + ":" + minutes + ":" + seconds;
}

let i = 1;
let aggregatedFrom = 0;

function processPart(res) {
  const arr = res.alternatives[0].words;
  let srt = "";
  let words = "";
  arr.forEach(({ startTime, endTime, word }) => {
    let to = parseInt(endTime.split(".")[0]);

    words += ` ${word}`;

    if (to - aggregatedFrom > 3) {
      srt += `${i++}\n`;
      srt += `${toHHMMSS(aggregatedFrom)} --> ${toHHMMSS(to)}\n`;
      srt += `${words}\n`;
      srt += `\n`;

      words = "";

      aggregatedFrom = to;
    }
  });

  return srt;
}

const parts = text.response.results.map(part => {
  return processPart(part);
});

let file = parts.reduce((agg, p) => `${agg}${p}`);

console.log(file);