raff.js

const raff = (render, raf = window.requestAnimationFrame) => {
  let redraw = false
  let args = null
  return (...yargs) => {
    if (args === null && !redraw) {
      redraw = true
      raf(() => {
        redraw = false
        render.apply(render,  args[args.length-1])
        args = null
      })
    }
    args = yargs
  }
}

const render = state => {
    console.log(state.now)
}

let draw = raff(render)

let prev = {}
const setState = state => {
  draw(state, prev)
  prev = state
}

setState({ now: date.now() })
setState({ now: date.now() })
setState({ now: date.now() })
setState({ now: date.now() })