A component which redraws on post-creation & pre-removal, providing `{born, to, die,}` as flags to the supplied function

BornToDie.js

const BornToDie = v => {
  let 
    born = true,
    to   = false,
    die  = false,
  
  let query
  
  let draw
  
  return {
    oncreate: v => {
      query = v.dom.clientHeight
      
      born = false
      to   = true
      
      requestAnimationFrame(draw)
    },
    
    onbeforeremove: v => (
      to  = false,
      die = true,
      
      draw(),
      
      new Promise(kill => {
        v.dom.addEventListener(
          'transitionend',
          kill,
        )
      })
    ),
    
    view: v => 
      m(Island, redraw => (
        draw = redraw,
        
        v.children[0].children({
          born,
          to,
          die,
        })
      ))
  }
}

@CreaturesInUnitards points out that waiting for any old transition end might cause a premature exit - in practice you can mitigate against this by stopping propagation on undesirable transition end events