Streak Calculator

The streak calculator tracks consecutive running days and maintains streak history.

How Streaks Work

A streak is a sequence of consecutive days where at least one run was recorded.

Rules

1. Multiple runs on the same day count as one day
2. A streak continues as long as you run at least once per day
3. Missing a day ends the current streak
4. A new streak starts with the next run

Streak Types

Current Streak

The number of consecutive days ending with today (or yesterday if today has no runs yet).

function getCurrentStreak(dailyStats: DailyStats[]): number {
  // Sort by date descending
  // Count consecutive days from most recent
}

Longest Streak

The longest consecutive run sequence ever recorded.

Streak History

All past streaks with start date, end date, and length.

API Response

{
  "streak": {
    "current": 5,
    "longest": 21,
    "history": [
      {
        "start": "2024-01-10",
        "end": "2024-01-30",
        "length": 21
      },
      {
        "start": "2024-02-05",
        "end": "2024-02-09",
        "length": 5
      }
    ]
  }
}

Implementation

The streak calculator is implemented in packages/business-logic/src/streak-calculator.ts.

import { calculateStreaks } from '@running-days/business-logic';

const streakData = calculateStreaks(dailyStats);
console.log(`Current streak: ${streakData.current} days`);

Edge Cases

Timezone Handling

Streaks are calculated in the user’s local timezone. A run at 11:59 PM counts for that day, not the next.

Same-Day Multiple Runs

If you run in the morning and evening, both contribute to daily stats, but you only get credit for one running day.

Future Dates

Runs with future dates are ignored in streak calculations.