MemCache.js

window.MemCache=(function () {
    var cache = Object.create(null);
    var debug = false;
    var hitCount = 0;
    var missCount = 0;
    var size = 0;

    function _del(key) {
        size--;
        delete cache[key];
    }

    function put(key, value, time, timeoutCallback) {
        if (debug) {
            console.log('caching: %s = %j (@%s)', key, value, time);
        }

        if (typeof time !== 'undefined' && (typeof time !== 'number' || isNaN(time) || time <= 0)) {
            throw new Error('Cache timeout must be a positive number');
        } else if (typeof timeoutCallback !== 'undefined' && typeof timeoutCallback !== 'function') {
            throw new Error('Cache timeout callback must be a function');
        }

        var oldRecord = cache[key];
        if (oldRecord) {
            clearTimeout(oldRecord.timeout);
        } else {
            size++;
        }

        var record = {
            value: value,
            expire: time + Date.now()
        };

        if (!isNaN(record.expire)) {
            record.timeout = setTimeout(function () {
                _del(key);
                if (timeoutCallback) {
                    timeoutCallback(key, value);
                }
            }, time);
        }

        cache[key] = record;

        return value;
    };

    function del(key) {
        var canDelete = true;

        var oldRecord = cache[key];
        if (oldRecord) {
            clearTimeout(oldRecord.timeout);
            if (!isNaN(oldRecord.expire) && oldRecord.expire < Date.now()) {
                canDelete = false;
            }
        } else {
            canDelete = false;
        }

        if (canDelete) {
            _del(key);
        }

        return canDelete;
    };

    function clear() {
        for (var key in cache) {
            clearTimeout(cache[key].timeout);
        }
        size = 0;
        cache = Object.create(null);
        if (debug) {
            hitCount = 0;
            missCount = 0;
        }
    };

    function get(key) {
        var data = cache[key];
        if (data) {
            if (isNaN(data.expire) || data.expire >= Date.now()) {
                if (debug) {
                    hitCount++;
                }
                return data.value;
            } else {
                if (debug) {
                    missCount++;
                }
                _del(key);
            }
        } else if (debug) {
            missCount++;
        }

        return null;
    };

    return {
        put: put,

        get: get,

        del: del,

        clear: clear,

        size: function () {
            return size;
        },

        memsize: function () {
            var size = 0;
            for (var key in cache) {
                size++;
            }
            return size;
        },

        debug: function (bool) {
            debug = bool;
        },

        hits: function () {
            return hitCount;
        },

        misses: function () {
            return missCount;
        },

        keys: function () {
            return Object.keys(cache);
        }
    };
})();