[Rise]

рони, чтение структуры (с мемоизацией):

var src = [
    [[2018], [2], [20], ['Event 1 (2018.02.20)', 'Event 2 (2018.02.20)']],
    [[2010, 2020], [7], [15], ['Event 3 (2010-2020.07.15)']],
    [[2015, 2017], [2, 4], [25], ['Event 4 (2015-2017.02-04.25)']],
    [[2006, 2008], [8, 10], [2, 6], ['Event 5 (2006-2008.08-10.02-06)']],
    [[2000, 2001], [5, 6], [10, 11], ['Event 6 (2000-2001.05-06.10-11)']],
];
var db = {
    data: src,
    cache: {},
    read: function (y, m, d) {
        var key = y + '.' + m + '.' + d, event = this.cache[key];
        if (event !== undefined) return event;
        var event = null, data = this.data;
        top: for (var i = 0; i < data.length; i++) {
            var list = data[i];
            for (var j = 0; j <= 3; j++) {
                var item = list[j];
                var date = arguments[j];
                if (j == 3) {
                    event = item;
                    break top;
                } else if (date < item[0] || (item.length == 1 ? date > item[0] : date > item[1])) {
                    break;
                }
            }
        }
        this.cache[key] = event;
        return event;
    }
};

// true dates tests

function D(y, m, d) {
    this.y = y;
    this.m = m;
    this.d = d;
};
var dates = [
    // 2018.02.20
    new D(2018, 02, 20),
    // 2010-2020.07.15
    new D(2010, 07, 15), new D(2020, 07, 15), new D(2011, 07, 15),
    // 2015-2017.02-04.25
    new D(2015, 02, 25), new D(2017, 02, 25), new D(2016, 02, 25),
    new D(2015, 04, 25), new D(2017, 04, 25), new D(2016, 04, 25),
    new D(2015, 03, 25), new D(2017, 03, 25), new D(2016, 03, 25),
    // 2006-2008.08-10.02-06
    new D(2006, 08, 02), new D(2008, 08, 02), new D(2007, 08, 02),
    new D(2006, 10, 02), new D(2008, 10, 02), new D(2007, 10, 02),
    new D(2006, 09, 02), new D(2008, 09, 02), new D(2007, 09, 02),
    new D(2006, 08, 06), new D(2008, 08, 06), new D(2007, 08, 06),
    new D(2006, 10, 06), new D(2008, 10, 06), new D(2007, 10, 06),
    new D(2006, 09, 06), new D(2008, 09, 06), new D(2007, 09, 06),
    new D(2006, 08, 03), new D(2008, 08, 03), new D(2007, 08, 03),
    new D(2006, 10, 03), new D(2008, 10, 03), new D(2007, 10, 03),
    new D(2006, 09, 03), new D(2008, 09, 03), new D(2007, 09, 03),
    // 2000-2001.05-06.10-11
    new D(2000, 05, 10), new D(2001, 05, 10),
    new D(2000, 06, 10), new D(2001, 06, 10),
    new D(2000, 05, 11), new D(2001, 05, 11),
    new D(2000, 06, 11), new D(2001, 06, 11),
];
dates.forEach(function (date, i) {
    var event = db.read(date.y, date.m, date.d);
    console.log(i, date, event);
});
Object.keys(db.cache).forEach(function (date, i) {
    var event = db.cache[date];
    console.log(i, date, event);
});