How close am I to the Fanatic badge on Stack Overflow?

stack-streak.js

$.get('/users/daily-site-access/' + StackExchange.options.user.userId, t => {
    eval(t.match(/var visited = {.+};/)[0]);
    const firstYear = Object.keys(visited)[0],
        firstMonth = Object.keys(visited[firstYear])[0],
        firstDay = Object.keys(visited[firstYear][firstMonth])[0],
        date = new Date(firstYear, firstMonth - 1, firstDay),
        today = Date.now();
    let days = [], seq = 0, streaks = [0], fewest = 100, fewestDate;
    do {
        days[++seq] = !!visited[date.getFullYear()][date.getMonth() + 1][date.getDate()];
        if (days[seq]) { streaks[streaks.length - 1]++; } else if (streaks[streaks.length - 1]) { streaks.push(0); }
        if (days.length >= 100) {
            // find 100-day period with fewest non-visits
            let missing = days.slice(-100).filter(v => v === false).length;
            if (missing <= fewest) { fewest = missing; fewestDate = new Date(date); }
        }
        date.setDate(date.getDate() + 1);
    } while (date < today);
  
    console.log(Math.max(...streaks), streaks, fewest, fewestDate);
});