Function placeholder

static/vuejs/vue.runtime.common.js:6487–6491

(h, rawChild)

}

function placeholder (h, rawChild) {
  return /\d-keep-alive$/.test(rawChild.tag)
    ? h('keep-alive')
    : null
}

function hasParentTransition (vnode) {
  while ((vnode = vnode.parent)) {