vue-intersect

VueJS plugin that reports element intersections using the IntersectionObserver API.

Installation

Via npm:

$ npm install @arnellebalane/vue-intersect

Via yarn:

$ yarn add @arnellebalane/vue-intersect

Usage

First, load the plugin. Depending on the environment, you have several options:

// ES6
import VueIntersect from '@arnellebalane/vue-intersect';

// AMD, e.g. RequireJS
require(['path/to/vue-intersect/dist/vue-intersect.js'], (VueIntersect) => { /**/ });

<!-- <script>, exposed as `VueIntersect`. -->
<script src="path/to/vue-intersect/dist/vue-intersect.js"></script>

<!-- or if you wanna load it via CDN (unpkg) -->
<script src="https://unpkg.com/@arnellebalane/vue-intersect@latest/dist/vue-intersect.umd.js"></script>

Then, tell Vue to use the plugin:

Vue.use(VueIntersect);

Then, add the v-intersect directive on the element whose intersection you want to observe:

<div v-intersect="onIntersect"></div>

export default {
    methods: {
        onIntersect(entry) {
            // Do something...
        }
    }
};

The value passed to the v-intersect directive is described in the API section.

IntersectionObserver Polyfill

This plugin uses the IntersectionObserver API under the hood. If a target browser does not support the API, we can use a polyfill for it.

However, as of v2.0.0 of this plugin, the polyfill for the IntersectionObserver API is not bundled anymore. This means that if you want to support browsers that don't natively support the API, you'd have to load the polyfill yourself.

This keeps the package size of this plugin very small and also keeps users from having to unnecessarily download the polyfill even when their browsers already support the IntersectionObserver API natively.

You may check out intersection-observer for steps on how to use the polyfill.

API

The v-intersect accepts either a Function or an Object.

If a Function is given, it will be used as the callback function which gets called whenever the element's intersection changes. The callback function is passed an IntersectionObserverEntry object, from which you can get the intersection ratio and other properties.

Passing a Function creates an IntersectionObserver using the default configurations. If you want to specify custom configurations, you should pass an Object to the v-intersect directive, which can contain the following keys:

• callback: Function. Required.
• threshold: Number or Array. Optional, defaults to 0.
• root: HTMLElement. Optional, defaults to null, which corresponds to the viewport itself.
• rootMargin: String. Optional, defaults to 0px.

I wrote an article explaning what the IntersectionObserver API and its terminologies.

License

MIT License