NervJS/nerv

var Monitoring =
  Monitoring ||
  (function() {
    var stats = new MemoryStats()
    stats.domElement.style.position = 'fixed'
    stats.domElement.style.right = '0px'
    stats.domElement.style.bottom = '0px'
    document.body.appendChild(stats.domElement)
    requestAnimationFrame(function rAFloop() {
      stats.update()
      requestAnimationFrame(rAFloop)
    })

    var RenderRate = function() {
      var container = document.createElement('div')
      container.id = 'stats'
      container.style.cssText =
        'width:150px;opacity:0.9;cursor:pointer;position:fixed;right:80px;bottom:0px;'

      var msDiv = document.createElement('div')
      msDiv.id = 'ms'
      msDiv.style.cssText =
        'padding:0 0 3px 3px;text-align:left;background-color:#020;'
      container.appendChild(msDiv)

      var msText = document.createElement('div')
      msText.id = 'msText'
      msText.style.cssText =
        'color:#0f0;font-family:Helvetica,Arial,sans-serif;font-size:9px;font-weight:bold;line-height:15px'
      msText.innerHTML = 'Repaint rate: 0/sec'
      msDiv.appendChild(msText)

      var self = this
      var rate = 0
      var bucketSize = 20
      var bucket = []
      var lastTime = Date.now()
      return {
        domElement: container,
        ping: function() {
          var start = lastTime
          var stop = Date.now()
          var rate = 1000 / (stop - start)
          if (rate == Infinity) {
            return
          }
          bucket.push(rate)
          if (bucket.length > bucketSize) {
            bucket.shift()
          }
          var sum = 0
          for (var i = 0; i < bucket.length; i++) {
            sum = sum + bucket[i]
          }
          self.rate = sum / bucket.length
          msText.textContent = 'Repaint rate: ' + self.rate.toFixed(2) + '/sec'
          lastTime = stop
        },
        rate: function() {
          return self.rate
        }
      }
    }

    var renderRate = new RenderRate()
    document.body.appendChild(renderRate.domElement)

    return {
      memoryStats: stats,
      renderRate: renderRate
    }
  })()