# Use @Action

What is an action? It is a string of characters sent to the script, formed as follows:

`action?nameAction=value`

For example, we can use them if we want \[create a persistent menu on Facebook Messenger] (<https://developers.facebook.com/docs/messenger-platform/send-messages/persistent-menu>), the JSON will be the following :

```javascript
{
  "persistent_menu":[
    {
      "locale":"default",
      "call_to_actions":[
        {
            "title":"Main Menu",
            "type":"postback",
            "payload": "action?menu"
        }
      ]
    }
  ]
}
```

When the user clicks the `Main Menu` button, an `action?menu` message will be sent to the script, of course invisible to the user.

### Action Decorator

To start a function in the script, let's use the decorator `@Action()`:

```typescript
@Action('menu')
menu() {
    > My menu
}
```

### If a value is sent

For example, with `action?menu=game`, we can use the magic variable `action`

```typescript
@Action('menu')
menu() {
    > Menu is { :action } // displays "Menu is game"
}
```