# lru-cache-ext

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Thin wrapper around lru-cache with extended functionality.

## Install

Install with [npm](https://www.npmjs.com/):

    $ npm install --save lru-cache-ext

## Usage

Please refer to [lru-cache](https://www.npmjs.com/package/lru-cache).

## Additional Options

### cacheNull

Type: `boolean`<br>
Default: `true`

When set to other than `true`, the `null` value is not cached with `memoize` and `memoizeSync`.

## Additional Functions

### memoize(key: String, valueFn: function, ...args)

Only when the key is not present in cache (or has expired), `valueFn` is called and placed into cache.

The cached value is returned when it becomes available (important in the case where `valueFn` is async).

The cache is left empty if an error is thrown at any point in `valueFn` (even asynchronous).

Useful when multiple async operation need to access the same async information.

### memoizeSync(key: String, valueFn: function, ...args)

Similar to "memoize", when key is not present (or has expired), `valueFn` is called and placed into the cache.

Cached value is returned from the function.

`valueFn` can be a synchronous or asynchronous function.

If `valueFn` is an asynchronous function and an error is thrown asynchronously, the cache is not invalidated.