change srt subtitle data to json using javascript

SrtToJson.js

// change minute time with milisecond to seconds
// e.g. 02:04:33,229
function toSeconds(input) {
    let a = input.split(',');
    let x = a[0].split(':').reverse().reduce((prev, curr, i) => prev + curr*Math.pow(60, i), 0);
    let y = a[1] / 1000
    return x + y;
}

function SrtToJson(srt) {
  let arr = srt.split('\n');
  arr = arr.filter(x => x.length > 0);
  arr = arr.filter(x => isNaN(x));
  let m = 0;
  let n = [];
  let next = false;
  arr.forEach(x => {
    if (!n[m]) n[m] = [];
    if (x.includes(' --> ')) {
      let z = x.split(' --> ');
      n[m][1] = toSeconds(z[0]);
      n[m][2] = toSeconds(z[1]);
    } else {
      n[m][0] = x;
      next = true;
    }
    if (next) {
      m++;
      next = false;
    }
  });
  return JSON.stringify(n)
}