trigger functions based on elements' positions, based on viewport

demo page

$ npm install vue-waypoint --save-dev

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

// Waypoint plugin
Vue.use(VueWaypoint)

VueWaypoint is a directive named v-waypoint

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

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!')
      }
    }
  }
}

• 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)

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) {}

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

• VueWaypoint.removeObserver (Element el, function callback)

• VueWaypoint.map

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.

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)