Time shift function to take an array of times and shift them. Works with Rhesus too.

timeshift.js

// timeshift.js
// node timeshift --file='newEvent.rhesus' --shift=+3000 --last
// node timeshift --file='lgf.starts.json' --shift=+690000

console.log('\nTIMESHIFT.JS');
console.log('> Automatically works with simple times or entire rhesus files.\n');

let argv = require('yargs').argv;

if (!argv.file) {
  console.log('> Please specify a --file flag.');
  process.exit(1);
}

if (!argv.shift) {
  console.log('> No --shift flag specified. Shifting by 0 time. Nothing will be changed.');
}else{
  console.log('> Shifting all ' + (argv.last ? 'last lap' : 'start') + ' times by ' + argv.shift + ' milliseconds.');
}

let
  fs = require('fs'),
  filename = argv.file, //either starttimes or rhesus file. Automatic detection
  shift = argv.shift || 0, // how much time to change (+ / -)
  shiftFirstTime = argv.last ? false : true, //whether to shif the first time (if not, then shift the last time)
  sourceData,
  modifiedData,
  outputFile = argv.outfile || filename.split('.')[ 0 ] + '('+shift+').' + filename.split('.')[ filename.split('.').length-1 ];


sourceData = JSON.parse(fs.readFileSync(filename, 'utf8'));

function isCategoryData(obj){return obj.hasOwnProperty('racers');}

// Assumes simple array of timestamps or durrations
if( Array.isArray(sourceData) ){

  if(!shiftFirstTime) { console.log('> Source data is a simple array: Ignoring "--last" flag.'); }  

  let i = sourceData.length;
  while(i--){
    if(sourceData[i] !== null){
      sourceData[i] += shift;
    }
  }

  modifiedData = JSON.stringify(sourceData, null, 2);
  fs.writeFile(outputFile, modifiedData, { flag : 'w' }, function(err) {
    if (err) throw err;
    console.log('> Saving ' + outputFile);
    console.log('> ALL DONE');
  });

}

// Assumes *.rhesus race file
// Operate accordingly
else if( sourceData.hasOwnProperty('eventName') ){

  // Shift event start time
  if(shiftFirstTime) { sourceData['eventStart'] += shift; }

  for(OBJ in sourceData){
    let CAT = sourceData[OBJ];
    if(isCategoryData(CAT)){

      // Shift category start time
      if(shiftFirstTime) { sourceData[OBJ]['startTime'] += shift; }

      for(let i = 0; i < CAT['racers'].length; i++){
        let
          RACER = CAT['racers'][i],
          TIMES = RACER[5],
          STARTTIME = TIMES[0][2],
          ENDTIME = TIMES[ RACER[5].length-1 ][2];

        // Shift racer start time
        if(shiftFirstTime) { sourceData[OBJ]['racers'][i][5][0][2] += shift; }

        // Shift racer finish time
        else { sourceData[OBJ]['racers'][i][5][ RACER[5].length-1 ][2] = ENDTIME + shift; }
      }
    }
  }

  modifiedData = JSON.stringify(sourceData, null, 2);
  fs.writeFile(outputFile, modifiedData, { flag : 'w' }, function(err) {
    if (err) throw err;
    console.log('> Saving ' + outputFile);
    console.log('> ALL DONE');
  });

}