VueWaypoint

trigger functions based on elements' positions, based on viewport

Demo

demo page

Installation

npm

$ npm install vue-waypoint --save-dev

Vue

import Vue from 'vue'
import VueWaypoint from 'vue-waypoint'

// Waypoint plugin
Vue.use(VueWaypoint)

Usage

VueWaypoint is a directive named v-waypoint

Template

<template>
  <div v-waypoint="{ active: true, callback: onWaypoint, options: intersectionOptions }"></div>
</template>

Javascript

export default {
  data: () => ({
    intersectionOptions: {
      root: null,
      rootMargin: '0px 0px 0px 0px',
      threshold: [0, 1] // [0.25, 0.75] if you want a 25% offset!
    } // https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API
  })
  methods: {
    onWaypoint ({ going, direction }) {
      // going: in, out
      // direction: top, right, bottom, left
      if (going === this.$waypointMap.GOING_IN) {
        console.log('waypoint going in!')
      }

      if (direction === this.$waypointMap.DIRECTION_TOP) {
        console.log('waypoint going top!')
      }
    }
  }
}

API

Directive's options

• active [boolean]: set this parameter as you wish, changing dynamically the waypoint status (it removes and adds the waypoint physically)

• callback [function]: every time the waypoint triggers this function will be called with a Waypoint object as parameter

• options [object]: you can leave this undefined or follow IntersectionObserver API (options)

Waypoint object

Each callback call comes with a Waypoint object defined as follows:

{
  el: Node,
  going: String,
  direction: String,
  _entry: IntersectionObserverEntry
}

You can map going and direction with the following global map, callable in every Vue's Component:

this.$waypointMap

Then you can compare map's elements with the callback's parameters:

if (direction === this.$waypointMap.DIRECTION_TOP) {}

Public API methods

• VueWaypoint.addObserver (Element el, function callback, Object options)

• VueWaypoint.removeObserver (Element el, function callback)

• VueWaypoint.map

Best practices

You are encouraged to use v-waypoint directive since it follows the Vue's flow, anyway you can progammatically add new waypoints as you like, even outside Vue's context.

This can be accomplished with addObserver and removeObserver.

You can call them inside Vue's components with this.$addObserver and this.$removeObserver.

They are also available as standalone-plugin, just go with VueWaypoint.addObserver and VueWaypoint.removeObserver.

Caveats

Waypoint first trigger is on page load, this means it actually triggers its own callback with direction = undefined (yes, we can't determine direction if no scroll has been made by the user)

How to use with Nuxt

You have to make certain changes when using vue-waypoint in a nuxt application mainly because it is designed for client side. Otherwise this could cause errors due to references to the window object.

1. Add the package to the project as usual

$ npm install vue-waypoint --save

2. Create new plugin file

Create new file under plugins folder and name it v-waypoint.client.js (.client suffix is required so it will be used only in the browser - see here)

3. Add the following code to v-waypoint.client.js to install the vue-waypoint

import Vue from "vue"
import VueWaypoint from "vue-waypoint"

Vue.use(VueWaypoint)

4. Update the nuxt.config.js to reference the plugin file

The mode: 'client' option will make sure v-waypoint is rendered and used only in the client-side bundle.

...
  plugins: [    
    ...
    { src: "~/plugins/v-waypoint.client.js",
      mode: 'client'
    }
  ],
...