# Routes transitions with Nuxt.js

> Nuxt.js uses the  [`<transition>`](http://vuejs.org/v2/guide/transitions.html#Transitioning-Single-Elements-Components) component to let you create amazing transitions/animations between your routes.

## Usage

🎬 [Demonstration video](https://www.youtube.com/watch?v=RIXOzJWFfc8)

**Nuxt.js default transition name is `page`.**

To add a fade transition to every page of your application, we need a CSS file that is shared across all our routes, so we start by creating a file in the `assets/` folder.

`assets/main.css`:
```css
.page-enter-active, .page-leave-active {
  transition: opacity .5s
}
.page-enter, .page-leave-active {
  opacity: 0
}
```

We add its path in our `nuxt.config.js` file:
```js
module.exports = {
  css: [
    'assets/main.css'
  ]
}
```

And voilà! A nice fade animation will be shown between every routes.

## The `transition` key

You can update the defaults transition settings by adding the `transition` key in you `nuxt.config.js` file.

```js
module.exports = {
  transition: 'test'
  // or
  transition: {
    name: 'test',
    mode: 'out-in'
  }
}
```

Nuxt.js will use these settings to set the component as follows:
```html
<transition name="test" mode="out-in">
```

To learn more about the Vue.js `<transition>` component: http://vuejs.org/v2/guide/transitions.html

The following properties that the `transition` key can have:

| key  | Type | Default | definition |
|------|------|---------|-----------|
| `name` | String | `"page"` | The transition name applied on all the routes transitions. |
| `mode` | String | `"out-in"` | The transition mode applied on all routes, see [Vue.js documentation](http://vuejs.org/v2/guide/transitions.html#Transition-Modes). |
| `css` | Boolean | `true` | Whether to apply CSS transition classes. Defaults to true. If set to false, will only trigger JavaScript hooks registered via component events. |
| `type` | String | `n/a` | Specify the type of transition events to wait for to determine transition end timing. Available values are "transition" and "animation". By default, it will automatically detect the type that has a longer duration. |
| `enterClass` | String | `n/a` | See [Vue.js documentation](https://vuejs.org/v2/guide/transitions.html#Custom-Transition-Classes) |
| `enterActiveClass` | String | `n/a` | See [Vue.js documentation](https://vuejs.org/v2/guide/transitions.html#Custom-Transition-Classes) |
| `leaveClass` | String | `n/a` | See [Vue.js documentation](https://vuejs.org/v2/guide/transitions.html#Custom-Transition-Classes) |
| `leaveActiveClass` | String | `n/a` | See [Vue.js documentation](https://vuejs.org/v2/guide/transitions.html#Custom-Transition-Classes) |

*Note: if the `transition` key is set as a string, it will be used as the `transition.name`.*

You can also define methods in the `transition`, these are for the [JavaScript hooks](https://vuejs.org/v2/guide/transitions.html#JavaScript-Hooks):

- `beforeEnter: function (el) { ... }`
- `enter: function (el, done) { ... }`
- `afterEnter: function (el) { ... }`
- `enterCancelled: function (el) { ... }`
- `beforeLeave: function (el) { ... }`
- `leave: function (el, done) { ... }`
- `afterLeave: function (el) { ... }`
- `leaveCancelled: function (el) { ... }`

*Note: it’s also a good idea to explicitly add `css: false` for JavaScript-only transitions so that Vue can skip the CSS detection. This also prevents CSS rules from accidentally interfering with the transition.*

## Custom transition on a specific route

To define a custom transition for a specific route, simply add the `transition` key to the page component:

`pages/about.vue`:
```html
<template>
  <div class="container">
    <h1>About page</h1>
    <nuxt-link to="/">Home page</nuxt-link>
  </div>
</template>

<script>
export default {
  transition: 'bounce'
}
</script>
```

And then we add the CSS animation for this custom transition:
```css
/* assets/main.css */
.bounce-enter-active {
  animation: bounce-in .8s;
}
.bounce-leave-active {
  animation: bounce-out .5s;
}
@keyframes bounce-in {
  0% { transform: scale(0) }
  50% { transform: scale(1.5) }
  100% { transform: scale(1) }
}
@keyframes bounce-out {
  0% { transform: scale(1) }
  50% { transform: scale(1.5) }
  100% { transform: scale(0) }
}
```

*Note: you can also the set `transition` key as an object in page components*

## Dynamic transition

To create a dynamic transition between two route depending on the route parameters, set the `transition` key as a `function`.

Example:
`pages/posts.vue`
```html
<script>
export default {
  transition (to, from) {
    if (!from) return 'slide-left'
    return +to.query.page < +from.query.page ? 'slide-right' : 'slide-left'
  }
}
</script>
```

## Demo

```bash
npm install
npm run dev
```

Go to [http://localhost:3000](http://localhost:3000) and navigate through the pages.