js创建一个构造函数的函数

var memoizer = function (memo, func) {
    var recur = function (n) {
        var result = memo[n];
        if (typeof result !== 'number') {
            result = func (recur, n);
        }
        return result;
    };
    return recur;
};

var fibonacci = memoizer([0, 1], function (recur, n) {
    return recur (n - 1) + recur(n - 2);
});