lazy-aggregator/README.md

Creates aggregation wrapper

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## lazy-aggregator

Create lazy-initialized dictionary based on `source` dictionary handled with `fn`

**Parameters**

-   `source` **[Object][1]&lt;[string][2], any>** dictionary of configs for `fn` call (optional, default `{}`)
-   `fn` **[function][3]** function which will be used to create elements in aggregation (optional, default `function(key,value){returnvalue}`)

**Examples**

```javascript
import Aggregation from 'lazy-aggregator';
const fn = (a) => a * 2;
const source = { el1: 1, el2: 2};

const aggregation = new Aggregation(source, fn);
aggregation['el1']; // 1
aggregation.el2; // 2
```

-   Throws **[Error][4]** if `fn` is not a function

## add

add element to aggregation

**Parameters**

-   `key` **[String][2]** first argument to `fn`
-   `value` **any?** data for `fn` call

**Examples**

```javascript
import Aggregation from 'lazy-aggregator';
import {add} from 'lazy-aggregator';
const fn = (a) => a * 2;
const source = { el1: 1, el2: 2};
const aggregation = new Aggregation({}, fn);
aggregation[add]('newEl', 2);
aggregation.newEl; // 4
```

Returns **[Object][1]** this

## del

delete element from aggregation

**Parameters**

-   `key` **[String][2]** key of aggregation member to delete

**Examples**

```javascript
import Aggregation from 'lazy-aggregator';
import {del} from 'lazy-aggregator';
const fn = (a) => a * 2;
const aggregation = new Aggregation({newEl: 3}, fn);
aggregation[del]('newEl');
aggregation.newEl; // undefined
```

Returns **[Object][1]** this

## Installation

npm install --save lazy-aggregator

[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function

[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error