fix plugin fold

Author: phphe

src/examples/Base.vue

@@ -15,10 +15,8 @@ div
       b Empty Tree
       Tree.base-tree(:value="treeDataEmpty" ref="tree4")
       hr
-      b Fola all at beginning:
-      br
-      code ref="tree" @hook:mounted="$refs.tree.foldAll()"
-      Tree.base-tree(:value="treeData2" ref="tree3" @hook:mounted="$refs.tree3.foldAll()")
+      b Fola all after mounted:
+      Tree.base-tree(:value="treeData2" ref="tree3" foldAllAfterMounted)
         div(slot-scope="{node, index, path, tree}")
           b(v-if="node.children && node.children.length > 0" @click="tree.toggleFold(node, path)") {{node.$folded ? '+' : '-'}} 
           input(type="checkbox" v-model="node.$checked" @change="tree.toggleCheck(node, path)")

src/examples/NodeBackTree.vue

@@ -2,7 +2,8 @@ import * as th from 'tree-helper'
 
 export default {
   props: {
-    foldingTransition: {},
+    foldingTransition: {type: String},
+    foldAllAfterMounted: {type: Boolean},
   },
   methods: {
     fold(node, path) {
@@ -42,4 +43,9 @@ export default {
       })
     },
   },
+  mounted() {
+    if (this.foldAllAfterMounted) {
+      this.foldAll()
+    }
+  },
 }