The item must have key field and must be unique，because Tree component use this for v-for directive set key property
\r\nrecommended use 0-1-1-3 structure,
\r\nand u'll see the benefits use this structure when u want dynamic modify treeData
\r\n\r\n showCheckbox: false,\r\n halfCheck: false\r\n \r\n \r\n showCheckbox: true,\r\n halfCheck: true\r\n \r\n , or missing
. Bailing hydration and performing ' +\n 'full client-side render.'\n );\n }\n }\n // either not server-rendered, or hydration failed.\n // create an empty node and replace it\n oldVnode = emptyNodeAt(oldVnode);\n }\n\n // replacing existing element\n var oldElm = oldVnode.elm;\n var parentElm$1 = nodeOps.parentNode(oldElm);\n\n // create new node\n createElm(\n vnode,\n insertedVnodeQueue,\n // extremely rare edge case: do not insert if old element is in a\n // leaving transition. Only happens when combining transition +\n // keep-alive + HOCs. (#4590)\n oldElm._leaveCb ? null : parentElm$1,\n nodeOps.nextSibling(oldElm)\n );\n\n // update parent placeholder node element, recursively\n if (isDef(vnode.parent)) {\n var ancestor = vnode.parent;\n var patchable = isPatchable(vnode);\n while (ancestor) {\n for (var i = 0; i < cbs.destroy.length; ++i) {\n cbs.destroy[i](ancestor);\n }\n ancestor.elm = vnode.elm;\n if (patchable) {\n for (var i$1 = 0; i$1 < cbs.create.length; ++i$1) {\n cbs.create[i$1](emptyNode, ancestor);\n }\n // #6513\n // invoke insert hooks that may have been merged by create hooks.\n // e.g. for directives that uses the \"inserted\" hook.\n var insert = ancestor.data.hook.insert;\n if (insert.merged) {\n // start at index 1 to avoid re-invoking component mounted hook\n for (var i$2 = 1; i$2 < insert.fns.length; i$2++) {\n insert.fns[i$2]();\n }\n }\n } else {\n registerRef(ancestor);\n }\n ancestor = ancestor.parent;\n }\n }\n\n // destroy old node\n if (isDef(parentElm$1)) {\n removeVnodes(parentElm$1, [oldVnode], 0, 0);\n } else if (isDef(oldVnode.tag)) {\n invokeDestroyHook(oldVnode);\n }\n }\n }\n\n invokeInsertHook(vnode, insertedVnodeQueue, isInitialPatch);\n return vnode.elm\n }\n}\n\n/* */\n\nvar directives = {\n create: updateDirectives,\n update: updateDirectives,\n destroy: function unbindDirectives (vnode) {\n updateDirectives(vnode, emptyNode);\n }\n};\n\nfunction updateDirectives (oldVnode, vnode) {\n if (oldVnode.data.directives || vnode.data.directives) {\n _update(oldVnode, vnode);\n }\n}\n\nfunction _update (oldVnode, vnode) {\n var isCreate = oldVnode === emptyNode;\n var isDestroy = vnode === emptyNode;\n var oldDirs = normalizeDirectives$1(oldVnode.data.directives, oldVnode.context);\n var newDirs = normalizeDirectives$1(vnode.data.directives, vnode.context);\n\n var dirsWithInsert = [];\n var dirsWithPostpatch = [];\n\n var key, oldDir, dir;\n for (key in newDirs) {\n oldDir = oldDirs[key];\n dir = newDirs[key];\n if (!oldDir) {\n // new directive, bind\n callHook$1(dir, 'bind', vnode, oldVnode);\n if (dir.def && dir.def.inserted) {\n dirsWithInsert.push(dir);\n }\n } else {\n // existing directive, update\n dir.oldValue = oldDir.value;\n callHook$1(dir, 'update', vnode, oldVnode);\n if (dir.def && dir.def.componentUpdated) {\n dirsWithPostpatch.push(dir);\n }\n }\n }\n\n if (dirsWithInsert.length) {\n var callInsert = function () {\n for (var i = 0; i < dirsWithInsert.length; i++) {\n callHook$1(dirsWithInsert[i], 'inserted', vnode, oldVnode);\n }\n };\n if (isCreate) {\n mergeVNodeHook(vnode, 'insert', callInsert);\n } else {\n callInsert();\n }\n }\n\n if (dirsWithPostpatch.length) {\n mergeVNodeHook(vnode, 'postpatch', function () {\n for (var i = 0; i < dirsWithPostpatch.length; i++) {\n callHook$1(dirsWithPostpatch[i], 'componentUpdated', vnode, oldVnode);\n }\n });\n }\n\n if (!isCreate) {\n for (key in oldDirs) {\n if (!newDirs[key]) {\n // no longer present, unbind\n callHook$1(oldDirs[key], 'unbind', oldVnode, oldVnode, isDestroy);\n }\n }\n }\n}\n\nvar emptyModifiers = Object.create(null);\n\nfunction normalizeDirectives$1 (\n dirs,\n vm\n) {\n var res = Object.create(null);\n if (!dirs) {\n return res\n }\n var i, dir;\n for (i = 0; i < dirs.length; i++) {\n dir = dirs[i];\n if (!dir.modifiers) {\n dir.modifiers = emptyModifiers;\n }\n res[getRawDirName(dir)] = dir;\n dir.def = resolveAsset(vm.$options, 'directives', dir.name, true);\n }\n return res\n}\n\nfunction getRawDirName (dir) {\n return dir.rawName || ((dir.name) + \".\" + (Object.keys(dir.modifiers || {}).join('.')))\n}\n\nfunction callHook$1 (dir, hook, vnode, oldVnode, isDestroy) {\n var fn = dir.def && dir.def[hook];\n if (fn) {\n try {\n fn(vnode.elm, dir, vnode, oldVnode, isDestroy);\n } catch (e) {\n handleError(e, vnode.context, (\"directive \" + (dir.name) + \" \" + hook + \" hook\"));\n }\n }\n}\n\nvar baseModules = [\n ref,\n directives\n];\n\n/* */\n\nfunction updateAttrs (oldVnode, vnode) {\n var opts = vnode.componentOptions;\n if (isDef(opts) && opts.Ctor.options.inheritAttrs === false) {\n return\n }\n if (isUndef(oldVnode.data.attrs) && isUndef(vnode.data.attrs)) {\n return\n }\n var key, cur, old;\n var elm = vnode.elm;\n var oldAttrs = oldVnode.data.attrs || {};\n var attrs = vnode.data.attrs || {};\n // clone observed objects, as the user probably wants to mutate it\n if (isDef(attrs.__ob__)) {\n attrs = vnode.data.attrs = extend({}, attrs);\n }\n\n for (key in attrs) {\n cur = attrs[key];\n old = oldAttrs[key];\n if (old !== cur) {\n setAttr(elm, key, cur);\n }\n }\n // #4391: in IE9, setting type can reset value for input[type=radio]\n // #6666: IE/Edge forces progress value down to 1 before setting a max\n /* istanbul ignore if */\n if ((isIE || isEdge) && attrs.value !== oldAttrs.value) {\n setAttr(elm, 'value', attrs.value);\n }\n for (key in oldAttrs) {\n if (isUndef(attrs[key])) {\n if (isXlink(key)) {\n elm.removeAttributeNS(xlinkNS, getXlinkProp(key));\n } else if (!isEnumeratedAttr(key)) {\n elm.removeAttribute(key);\n }\n }\n }\n}\n\nfunction setAttr (el, key, value) {\n if (isBooleanAttr(key)) {\n // set attribute for blank value\n // e.g. \n if (isFalsyAttrValue(value)) {\n el.removeAttribute(key);\n } else {\n // technically allowfullscreen is a boolean attribute for