关于找到任意组件实例的方法

function findComponentUpward(context, componentName) {
  let parent = context.$parent
  let name = parent.$options.name

  while (parent && (!name || [componentName].indexOf(name) < 0)) {
    parent = parent.$parent
    if (parent) name = parent.$options.name
  }
  return parent
}

function findComponentsUpward(context, componentName) {
  let parents = []
  const parent = context.$parent

  if (parent) {
    if (parent.$options.name === componentName) parents.push(parent)
    return parents.concat(findComponentsUpward(parent, componentName))
  } else {
    return []
  }
}

function findComponentDownward(context, componentName) {
  const childrens = context.$children
  let children = null

  if (childrens.length) {
    for (const child of childrens) {
      const name = child.$options.name

      if (name === componentName) {
        children = child
        break
      } else {
        children = findComponentDownward(child, componentName)
        if (children) break
      }
    }
  }
  return children
}

function findComponentsDownward(context, componentName) {
  return context.$children.reduce((components, child) => {
    if (child.$options.name === componentName) components.push(child)
    const foundChilds = findComponentsDownward(child, componentName)
    return components.concat(foundChilds)
  }, [])
}

function findBrothersComponents(context, componentName, exceptMe = true) {
  let res = context.$parent.$children.filter((item) => {
    return item.$options.name === componentName
  })
  let index = res.findIndex((item) => item._uid === context._uid)
  if (exceptMe) res.splice(index, 1)
  return res
}