# Vue compatibility

Docsify allows Vue content to be added directly to you markdown pages. This can greatly simplify working with data and adding reactivity to your site.

To get started, add Vue [2.x](https://vuejs.org) or [3.x](https://v3.vuejs.org) to your `index.html` file. Choose the production version for your live site or the development version for helpful console warnings and [Vue.js devtools](https://github.com/vuejs/vue-devtools) support.

#### Vue 2.x

```html
<!-- Production -->
<script src="//cdn.jsdelivr.net/npm/vue@2/dist/vue.min.js"></script>

<!-- Development -->
<script src="//cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
```

#### Vue 3.x

```html
<!-- Production -->
<script src="//cdn.jsdelivr.net/npm/vue@3/dist/vue.global.prod.js"></script>

<!-- Development -->
<script src="//cdn.jsdelivr.net/npm/vue@3/dist/vue.global.js"></script>
```

## Template syntax

Vue [template syntax](https://vuejs.org/v2/guide/syntax.html) is used to create dynamic content. With no additional configuration, this syntax offers several useful features like support for [JavaScript expressions](https://vuejs.org/v2/guide/syntax.html#Using-JavaScript-Expressions) and Vue [directives](https://vuejs.org/v2/guide/syntax.html#Directives) for loops and conditional rendering.

```markdown
<!-- Hide in docsify, show elsewhere (e.g. GitHub) -->
<p v-if="false">Text for GitHub</p>

<!-- Sequenced content (i.e. loop)-->
<ul>
  <li v-for="i in 3">Item {{ i }}</li>
</ul>

<!-- JavaScript expressions -->
<p>2 + 2 = {{ 2 + 2 }}</p>
```

<output data-lang="output">
  <p v-if="false">Text for GitHub</p>

  <ul>
    <li v-for="i in 3">Item {{ i }}</li>
  </ul>

  <p>2 + 2 = {{ 2 + 2 }}</p>
</output>

[View output on GitHub](https://github.com/docsifyjs/docsify/blob/develop/docs/vue.md#template-syntax)

Vue content becomes more interesting when [data](#data), [computed properties](#computed-properties), [methods](#methods), and [lifecycle hooks](#lifecycle-hooks) are used. These options can be specified as [global options](#global-options) or within DOM [mounts](#mounts) and [components](#components).

### Data

```js
{
  data() {
    return {
      message: 'Hello, World!'
    };
  }
}
```

<!-- prettier-ignore-start -->
```markdown
<!-- Show message in docsify, show "{{ message }}" elsewhere (e.g. GitHub)  -->
{{ message }}

<!-- Show message in docsify, hide elsewhere (e.g. GitHub)  -->
<p v-text="message"></p>

<!-- Show message in docsify, show text elsewhere (e.g. GitHub)  -->
<p v-text="message">Text for GitHub</p>
```
<!-- prettier-ignore-end -->

<output data-lang="output">

{{ message }}

  <p v-text="message"></p>
  <p v-text="message">Text for GitHub</p>
</output>

[View output on GitHub](https://github.com/docsifyjs/docsify/blob/develop/docs/vue.md#data)

### Computed properties

```js
{
  computed: {
    timeOfDay() {
      const date = new Date();
      const hours = date.getHours();

      if (hours < 12) {
        return 'morning';
      }
      else if (hours < 18) {
        return 'afternoon';
      }
      else {
        return 'evening'
      }
    }
  },
}
```

```markdown
Good {{ timeOfDay }}!
```

<output data-lang="output">

Good {{ timeOfDay }}!

</output>

### Methods

```js
{
  data() {
    return {
      message: 'Hello, World!'
    };
  },
  methods: {
    hello() {
      alert(this.message);
    }
  },
}
```

```markdown
<button @click="hello">Say Hello</button>
```

<output data-lang="output">
  <p><button @click="hello">Say Hello</button></p>
</output>

### Lifecycle Hooks

```js
{
  data() {
    return {
      images: null,
    };
  },
  created() {
    fetch('https://api.domain.com/')
      .then(response => response.json())
      .then(data => (this.images = data))
      .catch(err => console.log(err));
  }
}

// API response:
// [
//   { title: 'Image 1', url: 'https://domain.com/1.jpg' },
//   { title: 'Image 2', url: 'https://domain.com/2.jpg' },
//   { title: 'Image 3', url: 'https://domain.com/3.jpg' },
// ];
```

```markdown
<div style="display: flex;">
  <figure style="flex: 1;">
    <img v-for="image in images" :src="image.url" :title="image.title">
    <figcaption>{{ image.title }}</figcaption>
  </figure>
</div>
```

<output data-lang="output">
  <div style="display: flex;">
    <figure v-for="image in images" style="flex: 1; text-align: center;">
      <img :src="image.url">
      <figcaption>{{ image.title }}</figcaption>
    </figure>
  </div>
</output>

## Global options

Use `vueGlobalOptions` to specify [Vue options](https://vuejs.org/v2/api/#Options-Data) for use with Vue content not explicitly mounted with [vueMounts](#mounts), [vueComponents](#components), or a [markdown script](#markdown-script). Changes to global `data` will persist and be reflected anywhere global references are used.

```js
window.$docsify = {
  vueGlobalOptions: {
    data() {
      return {
        count: 0,
      };
    },
  },
};
```

```markdown
<p>
  <button @click="count -= 1">-</button>
  {{ count }}
  <button @click="count += 1">+</button>
</p>
```

<output data-lang="output">
  <p>
    <button @click="count -= 1">-</button>
    {{ count }}
    <button @click="count += 1">+</button>
  </p>
</output>

Notice the behavior when multiple global counters are rendered:

<output data-lang="output">
  <p>
    <button @click="count -= 1">-</button>
    {{ count }}
    <button @click="count += 1">+</button>
  </p>
</output>

Changes made to one counter affect the both counters. This is because both instances reference the same global `count` value. Now, navigate to a new page and return to this section to see how changes made to global data persist between page loads.

## Mounts

Use `vueMounts` to specify DOM elements to mount as [Vue instances](https://vuejs.org/v2/guide/instance.html) and their associated options. Mount elements are specified using a [CSS selector](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Selectors) as the key with an object containing Vue options as their value. Docsify will mount the first matching element in the main content area each time a new page is loaded. Mount element `data` is unique for each instance and will not persist as users navigate the site.

```js
window.$docsify = {
  vueMounts: {
    '#counter': {
      data() {
        return {
          count: 0,
        };
      },
    },
  },
};
```

```markdown
<div id="counter">
  <button @click="count -= 1">-</button>
  {{ count }}
  <button @click="count += 1">+</button>
</div>
```

<output id="counter">
  <button @click="count -= 1">-</button>
  {{ count }}
  <button @click="count += 1">+</button>
</output>

## Components

Use `vueComponents` to create and register global [Vue components](https://vuejs.org/v2/guide/components.html). Components are specified using the component name as the key with an object containing Vue options as the value. Component `data` is unique for each instance and will not persist as users navigate the site.

```js
window.$docsify = {
  vueComponents: {
    'button-counter': {
      template: `
        <button @click="count += 1">
          You clicked me {{ count }} times
        </button>
      `,
      data() {
        return {
          count: 0,
        };
      },
    },
  },
};
```

```markdown
<button-counter></button-counter>
<button-counter></button-counter>
```

<output data-lang="output">
  <button-counter></button-counter>
  <button-counter></button-counter>
</output>

## Markdown script

Vue content can mounted using a `<script>` tag in your markdown pages.

!> Only the first `<script>` tag in a markdown file is executed. If you wish to mount multiple Vue instances using a script tag, all instances must be mounted within the first script tag in your markdown.

```html
<!-- Vue 2.x  -->
<script>
  new Vue({
    el: '#example',
    // Options...
  });
</script>
```

```html
<!-- Vue 3.x  -->
<script>
  Vue.createApp({
    // Options...
  }).mount('#example');
</script>
```

## Technical Notes

- Docsify processes Vue content in the following order on each page load:
  1. Execute markdown `<script>`
  1. Register global `vueComponents`
  1. Mount `vueMounts`
  1. Auto-mount unmounted `vueComponents`
  1. Auto-mount unmounted Vue template syntax using `vueGlobalOptions`
- When auto-mounting Vue content, docsify will mount each top-level element in your markdown that contains template syntax or a component. For example, in the following HTML the top-level `<p>`, `<my-component />`, and `<div>` elements will be mounted.
  ```html
  <p>{{ foo }}</p>
  <my-component />
  <div>
    <span>{{ bar }}</span>
    <some-other-component />
  </div>
  ```
- Docsify will not mount an existing Vue instance or an element that contains an existing Vue instance.
- Docsify will automatically destroy/unmount all Vue instances it creates before each page load.
