{{#block "logo"}}{{/block}}
## Usage

```js
var mapVisit = require('{%= name %}');
```

## Assign or Merge vs. Visit

Let's say you want to add a `set` method to your application that will:

- set key-value pairs on a `data` object
- extend objects onto the `data` object
- extend arrays of objects onto the data object

**Example using `extend`**

Here is one way to accomplish this using Lo-Dash's `extend`:

```js
var _ = require('lodash');

var obj = {
  data: {},
  set: function (key, value) {
    if (Array.isArray(key)) {
      _.extend.apply(_, [obj.data].concat(key));
    } else if (typeof key === 'object') {
      _.extend(obj.data, key);
    } else {
      obj.data[key] = value;
    }
  }
};

obj.set('a', 'a');
obj.set([{b: 'b'}, {c: 'c'}]);
obj.set({d: {e: 'f'}});

console.log(obj.data);
//=> {a: 'a', b: 'b', c: 'c', d: { e: 'f' }}
```

The above approach works fine for most use cases. But **if you also want to emit an event** each time a property is added to the `data` object. A better approach would be to use `visit`.

**Example using `visit`**

In this approach, when an array is passed to `set`, `mapVisit` calls `set` on each object in the array. When an object is passed, `visit` calls `set` on each property in the object. As a result, the `data` event will be emitted every time a property is added to `data`.

```js
var mapVisit = require('{%= name %}');
var visit = require('object-visit');

var obj = {
  data: {},
  set: function (key, value) {
    if (Array.isArray(key)) {
      mapVisit(obj, 'set', key);
    } else if (typeof key === 'object') {
      visit(obj, 'set', key);
    } else {
      // some event-emitter
      console.log('emit', key, value);
      obj.data[key] = value;
    }
  }
};

obj.set('a', 'a');
obj.set([{b: 'b'}, {c: 'c'}]);
obj.set({d: {e: 'f'}});
obj.set({g: 'h', i: 'j', k: 'l'});

console.log(obj.data);
//=> {a: 'a', b: 'b', c: 'c', d: { e: 'f' }, g: 'h', i: 'j', k: 'l'}

// events would look something like:
// emit a a
// emit b b
// emit c c
// emit d { e: 'f' }
// emit g h
// emit i j
// emit k l
```