utils.js

var log = console.log.bind(console);
var random = function (start, end) {
    start = start === void 0 ? 0 : start;
    end = end === void 0 ? 1 : end;
    end = end + 1;
    var rand = Math.random() * (end - start) + start;
    return Math.floor(rand);
};
var $ = function (elem) {
    return document.querySelectorAll(elem);
}
var on = function (elem, type, callback) {
    elem.addEventListener(type, function (e) {
        callback(e);
    });
}

var indexToPos = function (index) {
    return {
        x: index % 4,
        y: Math.floor(index / 4),
    }
}

var getLocalStorage = function (key) {
    return localStorage[key] ?
        JSON.parse(localStorage[key]) : null;
}

var touchMoveDir = function (elem, min, callback) {
    var touchPos = {
        beforeX: 0,
        beforeY: 0,
        afterX: 0,
        afterY: 0,
    }
    var move = false;
    var dir;
    on(elem, 'touchstart', function (e) {
        touchPos.beforeX = e.touches[0].clientX;
        touchPos.beforeY = e.touches[0].clientY;
    });
    on(elem, 'touchmove', function (e) {
        move = true;
        touchPos.afterX = e.touches[0].clientX;
        touchPos.afterY = e.touches[0].clientY;
    });
    on(elem, 'touchend', function (e) {
        if (!move) return;
        var x = touchPos.beforeX - touchPos.afterX;
        var y = touchPos.beforeY - touchPos.afterY;
        log(x, y);
        if (Math.abs(x) < min && Math.abs(y) < min) {
            return;
        }
        if (Math.abs(x) > Math.abs(y)) {
            dir = x > 0 ? 0 : 2;
        } else {
            dir = y > 0 ? 1 : 3;
        }
        move = false;
        callback(dir);
    });
};