Vue 2 directive that sets CSS classes on its host element based on the elements current position in the viewport. These classes are:

• in-viewport - Some part of the element is within the viewport
• above-viewport - Some part of the element is above the viewport
• below-viewport - Some part of the element is below the viewport

You may want to check out the mixin version of this package: vue-in-viewport-mixin.

Demo: https://bkwld.github.io/vue-in-viewport-directive

Note, this should not be applied to elements / components that are setting a dynamic class through Vue. See this issue.

• Register the directive:

   import Vue from 'vue'
   import inViewportDirective from 'vue-in-viewport-directive'
   Vue.directive('in-viewport', inViewportDirective)

• Use the classes to trigger CSS transitions (for instance):

   <div class='box' v-in-viewport></div>
   <div class='box' v-in-viewport.once='-100px 0px'></div>
   <div class='box' v-in-viewport.once='{ margin: "-10% 0%" }'></div>

   .box {
   	opacity: 0;
   	transition: opacity .3s;
   }
   .box.in-viewport {
   	opacity: 1;
   }

• Set default offsets:

import inViewportDirective from 'vue-in-viewport-directive'
inViewportDirective.defaults.margin = '-10% 0%'
Vue.directive('in-viewport', inViewportDirective)

• Compatibility note: This package requires IE >= 10 because it uses classList. Polyfill classList if you need to support older browsers.
• Compatibility note: This package a polyfill for IntersectionObserver in browsers like IE.

You can disable all updates and re-enable them globally:

import { enable, disable } from 'vue-in-viewport-directive'
disable()
setTimeout(enable, 500)

This can be used during full page transitions to trigger all the in viewport transitions only once the page transition finishes.

• once - Whether to remove listeners once the element enters viewport. If the element is in viewport when mounted, listeners are never added.

• Set the value to a string in the style of IntersectionObserver rootMargin to apply an offset to when the in viewport classes get added.

   <div v-in-viewport="'-100px 0px'"></div>

• Or, set it via an option:

   <div v-in-viewport='{ margin: "-100px 0px" }'></div>

• Conditionally disable with disabled:

   <div v-in-viewport='{ disabled: true }'></div>

1. Start Storybook: yarn storybook
2. Open Cypress: yarn cypress open

The Travis tests that run on deploy run against the demo site which gets updated as part of the npm version