# vue-scrollactive

This component makes it simple to highlight a menu item with an 'active' class as you scroll.

- Highlights items with a class as you scroll
- Scrolls to item's section on click
- Configurable easing scroll effect
- Emits events for full control

Make sure to check the [demo](https://eddiemf.github.io/vue-scrollactive/dist) where you can play around with every option.

## Installation

Install using `yarn`

```bash
yarn add vue-scrollactive
```

or `npm`

```bash
npm install --save vue-scrollactive
```

then install the plugin

```js
import VueScrollactive from 'vue-scrollactive';

Vue.use(VueScrollactive);
```

Or if you wish to include it in a `script` tag, just download the source code from the latest release [here](https://github.com/eddiemf/vue-scrollactive/releases/latest) and include the `vue-scrollactive.min.js` file located in the `dist` folder in your page as a script:

```html
<script src="dist/vue-scrollactive.min.js"></script>
```

If you're not running any transpiler like babel, you'll most likely need to install a Promise polyfill such as [this](https://github.com/taylorhakes/promise-polyfill) to support older browsers since this library depends on promises to work.

## Usage

The primary way to use the plugin is to wrap your menu in a `<scrollactive>` tag (which will be your nav) and add a `.scrollactive-item` class in your `<a>` tags as I show in the example below:

```html
<scrollactive class="my-nav">
  <a href="#home" class="scrollactive-item">Home</a>
  <a href="#about-us" class="scrollactive-item">About Us</a>
  <a href="#portfolio" class="scrollactive-item">Portfolio</a>
  <a href="#contact" class="scrollactive-item">Contact</a>
</scrollactive>
```

You can follow whatever structure you wish, just make sure to set the `.scrollactive-item` class in the items you want to highlight and set its `href` with a valid element ID that you would like to track while scrolling.

The secondary way to use it is almost the same as the primary but instead of relying on `href` to find your sections you'll need to set a data attribute `data-section-selector` on your elements with the section selector you wish to have.

```html
<scrollactive class="my-nav">
  <span data-section-selector="#home" class="scrollactive-item">Home</span>
  <span data-section-selector=".about-us" class="scrollactive-item">About Us</span>
  <span data-section-selector=".portfolio div span" class="scrollactive-item">Portfolio</span>
  <span data-section-selector="#contact" class="scrollactive-item">Contact</span>
</scrollactive>
```

As you can see this gives you more freedom to choose different tags and you can use whatever CSS selector you find necessary, but it's important to notice that `data-section-selector` takes precedence over `href`, so if you have a tag `<a href="#section-1" data-section-selector="#another-section">` it will completely ignore the `#section-1` and use `#another-section` instead.

## Events

Scrollactive will emit an `itemchanged(event, currentItem, lastActiveItem)` event when an active menu item is changed to another. You can catch that event doing as the example below:

```html
<scrollactive class="my-nav" v-on:itemchanged="onItemChanged">
  <a href="#home" class="scrollactive-item">Home</a>
  <a href="#about-us" class="scrollactive-item">About Us</a>
  <a href="#portfolio" class="scrollactive-item">Portfolio</a>
  <a href="#contact" class="scrollactive-item">Contact</a>
</scrollactive>
```

```javascript
// ...
methods: {
  onItemChanged(event, currentItem, lastActiveItem) {
    // here you have access to everything you need regarding that event
  },
},
// ...
```

## Configuration

All options should be passed as a prop in the `<scrollactive>` component as you can see in the example below:

```html
<scrollactive active-class="active" :offset="80" :duration="800" bezier-easing-value=".5,0,.35,1">
</scrollactive>
```

Remember that all options are optional and you can check the default values below:

### Options

```javascript
/**
 * Active class that will be applied to the active item.
 */
activeClass: {
  type: String,
  default: 'is-active',
},

/**
 * Amount of space between top of screen and the section to highlight. (Usually your fixed
 * header's height).
 */
offset: {
  type: Number,
  default: 20,
},

/**
 * Amount of space between the top of the screen and the section to highlight when clicking a
 * scrollactive item to scroll. It will use the value of the `offset` prop if none is provided
 * here. Useful when you want to use the `offset` prop to make an item be active as soon as
 * it shows on the screen but still scroll to the top of the section when clicking the item.
 */
scrollOffset: {
  type: Number,
  default: null,
},

/**
 * The selector string of the scroll container element you'd like to use. It defaults to the
 * window object (most common), but you might want to change in case you're using an element
 * as container with overflow.
 */
scrollContainerSelector: {
  type: String,
  default: '',
},

/**
 * Enables/disables the scrolling when clicking in a menu item.
 * Disable if you'd like to handle the scrolling by your own.
 */
clickToScroll: {
  type: Boolean,
  default: true,
},

/**
 * The duration of the scroll animation when clicking to scroll is activated.
 */
duration: {
  type: Number,
  default: 600,
},

/**
 * Defines if the plugin should track the section change when clicking an item to scroll to
 * its section. If set to true, it will always keep track and change the active class to the
 * current section while scrolling, if false, the active class will be immediately applied to
 * the clicked menu item, ignoring the passed sections until the scrolling is over.
 */
alwaysTrack: {
  type: Boolean,
  default: false,
},

/**
 * Your custom easing value for the click to scroll functionality.
 * It must be a string with 4 values separated by commas in a cubic bezier format.
 */
bezierEasingValue: {
  type: String,
  default: '.5,0,.35,1',
},

/**
 * Decides if the URL should be modified with the section id when clicking a scrollactive
 * item.
 */
modifyUrl: {
  type: Boolean,
  default: true,
},

/**
 * If true the active class will only be applied when a section matches exactly one of the
 * scrollactive items, meaning it will be highlighted when scrolling exactly inside the
 * section. If false (default) it will always highlight the last item which was matched
 * in a section, even if it is already outside that section (and not inside another that's
 * being tracked).
 */
exact: {
  type: Boolean,
  default: false,
},

/**
 * If true the active class will be applied to the first scrollactive-item before you scroll
 * past it (even if you didn't reach it yet).
 */
highlightFirstItem: {
  type: Boolean,
  default: false,
},

/**
 * Changes the scrollactive container component html tag.
 */
tag: {
  type: String,
  default: 'nav',
},

/**
 * If true the screen will scroll down to the element in the URL when the component is mounted.
 */
scrollOnStart: {
  type: Boolean,
  default: true,
},
```

## Contributing

Clone the repository and install the dependencies running `yarn`. After the dependencies are installed you should be good to run `yarn start` which will load up a server with the sandbox for you to play around.