Function patchVnode

chapter17/vue.js:6259–6332

(
      oldVnode,
      vnode,
      insertedVnodeQueue,
      ownerArray,
      index,
      removeOnly
    )

    }

    function patchVnode (
      oldVnode,
      vnode,
      insertedVnodeQueue,
      ownerArray,
      index,
      removeOnly
    ) {
      if (oldVnode === vnode) {
        return
      }

      if (isDef(vnode.elm) && isDef(ownerArray)) {
        // clone reused vnode
        vnode = ownerArray[index] = cloneVNode(vnode);
      }

      var elm = vnode.elm = oldVnode.elm;

      if (isTrue(oldVnode.isAsyncPlaceholder)) {
        if (isDef(vnode.asyncFactory.resolved)) {
          hydrate(oldVnode.elm, vnode, insertedVnodeQueue);
        } else {
          vnode.isAsyncPlaceholder = true;
        }
        return
      }

      // reuse element for static trees.
      // note we only do this if the vnode is cloned -
      // if the new node is not cloned it means the render functions have been
      // reset by the hot-reload-api and we need to do a proper re-render.
      if (isTrue(vnode.isStatic) &&
        isTrue(oldVnode.isStatic) &&
        vnode.key === oldVnode.key &&
        (isTrue(vnode.isCloned) || isTrue(vnode.isOnce))
      ) {
        vnode.componentInstance = oldVnode.componentInstance;
        return
      }

      var i;
      var data = vnode.data;
      if (isDef(data) && isDef(i = data.hook) && isDef(i = i.prepatch)) {
        i(oldVnode, vnode);
      }

      var oldCh = oldVnode.children;
      var ch = vnode.children;
      if (isDef(data) && isPatchable(vnode)) {
        for (i = 0; i < cbs.update.length; ++i) { cbs.update[i](oldVnode, vnode); }
        if (isDef(i = data.hook) && isDef(i = i.update)) { i(oldVnode, vnode); }
      }
      if (isUndef(vnode.text)) {
        if (isDef(oldCh) && isDef(ch)) {
          if (oldCh !== ch) { updateChildren(elm, oldCh, ch, insertedVnodeQueue, removeOnly); }
        } else if (isDef(ch)) {
          {