Rate limit for api requests from https://github.com/axios/axios/issues/230

api.js

function promiseDebounce(fn, delay, count) {
  var working = 0, queue = []
  function work() {
    if ((queue.length === 0) || (working === count)) return
    working++

    new Promise(function(resolve, reject){
      setTimeout(function(){
        working--
        work()
      }, delay)
    })
    var next = queue.shift()
    next[2](fn.apply(next[0], next[1]))
  }
  return function debounced() {
    var args = arguments
    return new Promise(function(resolve){
      queue.push([this, args, resolve])
      if (working < count) work()
    }.bind(this))
  }
}