Mithril's api/redraw.js, rewritten to throttle globally, support sync redraws, and be simpler.

api-redraw.js

"use strict"

var coreRenderer = require("../render/render")

function throttle(callback) {
  //60fps translates to 16.6ms, round it down since setTimeout requires int
  var delay = 16, last = 0, pending
  var timeout = typeof requestAnimationFrame === "function" ? requestAnimationFrame : setTimeout
  return function() {
    if (pending == null) {
      pending = timeout(function() {
        pending = undefined
        callback()
        last = Date.now()
      }, delay - Date.now() - last)
    }
  }
}

module.exports = function($window, throttleMock) {
  var _throttle = throttleMock || throttle
  var renderService = coreRenderer($window)
  var roots = [], callbacks = []
  var redraw = _throttle(redrawSync)
  var locked = false

  renderService.setEventCallback(function(e) {
    if (e.redraw !== false) redraw()
  })

  function unsubscribe(key) {
    var index = callbacks.indexOf(key)
    if (index > -1) callbacks.splice(index, 2)
  }

  function subscribe(key, callback) {
    unsubscribe(key)
    callbacks.push(key, callback)
  }

  function redrawSync() {
    if (locked) throw new Error("Can't redraw synchronously while already redrawing")
    locked = true
    for (var i = 1; i < callbacks.length; i += 2) callbacks[i]()
    locked = false
  }

  return {subscribe: subscribe, unsubscribe: unsubscribe, redraw: redraw, redrawSync: redrawSync, render: renderService.render}
}