code: function postpatch(oldVnode, vnode) {
    const oldData = oldVnode.data
    const newData = vnode.data
  
    // Server side rendering: Reconcilating with a server-rendered node will have skipped calling insert()
    if (!oldData.component) {
      insert(vnode)
    }
  
    // oldData wouldn't have a component reference set if it came from the server (it's first set in insert())
    const component = oldData.component || newData.component
    const oldProps = component.props
    const newProps = newData.component.props
  
    // Update the original component with any property that may have changed during this render pass
    component.props = newProps
  
    newData.component = component
  
    // If the props changed, render immediately as we are already
    // in the render context of our parent
    if (!shallowEqual(oldProps, newProps)) {
  
      component.lifecycle.propsChanging = true
      component.lifecycle.propsChanged(newProps)
      component.lifecycle.propsChanging = false
  
      renderComponentNow(component)
    }
  }
docs: Called on every parent re-render, this is where the props passed by the component's parent may have changed.