a standalone memoize function inspired by lodash

memoize.js

function memoize(func, resolver) {
    var memoized = function() {
        var cache = memoized.cache;
        var key = resolver ?
                resolver.apply(this, arguments) :
                arguments[0];

        if (cache.has(key)) {
            return cache.get(key);
        }

        var result = func.apply(this, arguments);
        cache.set(key, result);
        return result;
    };

    // Must have pollyfill available for Map if compatibility for older browsers is desired
    memoized.cache = new Map();
    return memoized;
}