Yield differences in parsing dates from log vs event log timestamp

diffs.js

const moment = require('moment');

const format1 = require('./format1_log_events.json');
const format2 = require('./format2_log_events.json');

const events = {
  format1,
  format2
};

const allDiffs = Object.keys(events).map(key => ({ key, events: events[key] })).map(stream => {
  const logStream = stream.key;
  const diffs = stream.events.map((event) => {
    let ingestionTime = moment(event.ingestionTime);
    let timestamp = moment(event.timestamp);

    let dateStr = event.message.split('"')[1];
    let actualDate = moment(dateStr);

    return {
      actualDate: actualDate.toISOString(),
      ingestion: {
        time: ingestionTime.toISOString(),
        diff: ingestionTime.diff(actualDate, 'seconds', true)
      },
      timestamp: {
        time: timestamp.toISOString(),
        diff: timestamp.diff(actualDate, 'seconds', true)
      },
    };
  });

  return { logStream, diffs };
});

console.log(JSON.stringify(allDiffs));

format1_log_events.json

[
  {
    "ingestionTime": 1492003986633,
    "timestamp": 1492003980458,
    "message": "time=\"2017-04-12T13:32:46Z\" level=info msg=\"daemon starting\" pid=1234 version=1.0.1 "
  },
  {
    "ingestionTime": 1492003986633,
    "timestamp": 1492003980458,
    "message": "time=\"2017-04-12T13:32:46Z\" level=info msg=\"Attempting operation\" server_path=\"/var/lib/daemon/dev.server\" "
  }
]

format2_log_events.json

[
  {
    "ingestionTime": 1492003986676,
    "timestamp": 1492003966000,
    "message": "time=\"2017-04-12T13:32:46Z\" level=info msg=\"daemon starting\" pid=1234 version=1.0.1 "
  },
  {
    "ingestionTime": 1492003986676,
    "timestamp": 1492003966000,
    "message": "time=\"2017-04-12T13:32:46Z\" level=info msg=\"Attempting operation\" server_path=\"/var/lib/daemon/dev.server\" "
  }
]

sample.output.json

[
  {
    "logStream": "format1",
    "diffs": [
      {
        "actualDate": "2017-04-12T13:32:46.000Z",
        "ingestion": {
          "time": "2017-04-12T13:33:06.633Z",
          "diff": 20.633
        },
        "timestamp": {
          "time": "2017-04-12T13:33:00.458Z",
          "diff": 14.458
        }
      },
      {
        "actualDate": "2017-04-12T13:32:46.000Z",
        "ingestion": {
          "time": "2017-04-12T13:33:06.633Z",
          "diff": 20.633
        },
        "timestamp": {
          "time": "2017-04-12T13:33:00.458Z",
          "diff": 14.458
        }
      }
    ]
  },
  {
    "logStream": "format2",
    "diffs": [
      {
        "actualDate": "2017-04-12T13:32:46.000Z",
        "ingestion": {
          "time": "2017-04-12T13:33:06.676Z",
          "diff": 20.676
        },
        "timestamp": {
          "time": "2017-04-12T13:32:46.000Z",
          "diff": 0
        }
      },
      {
        "actualDate": "2017-04-12T13:32:46.000Z",
        "ingestion": {
          "time": "2017-04-12T13:33:06.676Z",
          "diff": 20.676
        },
        "timestamp": {
          "time": "2017-04-12T13:32:46.000Z",
          "diff": 0
        }
      }
    ]
  }
]