mjz update

vdoing/components/DropdownTransition.vue

@@ -0,0 +1,32 @@
+<template>
+  <transition
+    name="dropdown"
+    @enter="setHeight"
+    @after-enter="unsetHeight"
+    @before-leave="setHeight"
+  >
+    <slot />
+  </transition>
+</template>
+
+<script>
+export default {
+  name: 'DropdownTransition',
+
+  methods: {
+    setHeight (items) {
+      // explicitly set height so that it can be transitioned
+      items.style.height = items.scrollHeight + 'px'
+    },
+
+    unsetHeight (items) {
+      items.style.height = ''
+    }
+  }
+}
+</script>
+
+<style lang="stylus">
+.dropdown-enter, .dropdown-leave-to
+  height 0 !important
+</style>