first steps in intersection-observer directive

src/plugins/intersection-observer.js

 export default ({ Vue }) => {
   Vue.directive('intersection-observer', {
     inserted: function (el) {
-      el.style.backgroundColor = 'green'
+      const options = {
+        root: null,
+        threshold: '0'
+      }
+      const observer = new IntersectionObserver(observerCallback, options)
+      observer.observe(el)
+
+      function observerCallback (entries) {
+        entries.forEach(entry => {
+          if (entry.isIntersecting) {
+            console.log('isIntersecting')
+          }
+          else {
+            console.log('nicht mehr intersecting')
+            console.log(entry.boundingClientRect.left)
+          }
+        })
+      }
     }
   })
 }