1let len = 0; 2let vertxNext; 3let customSchedulerFn; 4 5export var asap = function asap(callback, arg) { 6 queue[len] = callback; 7 queue[len + 1] = arg; 8 len += 2; 9 if (len === 2) { 10 // If len is 2, that means that we need to schedule an async flush. 11 // If additional callbacks are queued before the queue is flushed, they 12 // will be processed by this flush that we are scheduling. 13 if (customSchedulerFn) { 14 customSchedulerFn(flush); 15 } else { 16 scheduleFlush(); 17 } 18 } 19} 20 21export function setScheduler(scheduleFn) { 22 customSchedulerFn = scheduleFn; 23} 24 25export function setAsap(asapFn) { 26 asap = asapFn; 27} 28 29const browserWindow = (typeof window !== 'undefined') ? window : undefined; 30const browserGlobal = browserWindow || {}; 31const BrowserMutationObserver = browserGlobal.MutationObserver || browserGlobal.WebKitMutationObserver; 32const isNode = typeof self === 'undefined' && typeof process !== 'undefined' && {}.toString.call(process) === '[object process]'; 33 34// test for web worker but not in IE10 35const isWorker = typeof Uint8ClampedArray !== 'undefined' && 36 typeof importScripts !== 'undefined' && 37 typeof MessageChannel !== 'undefined'; 38 39// node 40function useNextTick() { 41 // node version 0.10.x displays a deprecation warning when nextTick is used recursively 42 // see https://github.com/cujojs/when/issues/410 for details 43 return () => process.nextTick(flush); 44} 45 46// vertx 47function useVertxTimer() { 48 if (typeof vertxNext !== 'undefined') { 49 return function() { 50 vertxNext(flush); 51 }; 52 } 53 54 return useSetTimeout(); 55} 56 57function useMutationObserver() { 58 let iterations = 0; 59 const observer = new BrowserMutationObserver(flush); 60 const node = document.createTextNode(''); 61 observer.observe(node, { characterData: true }); 62 63 return () => { 64 node.data = (iterations = ++iterations % 2); 65 }; 66} 67 68// web worker 69function useMessageChannel() { 70 const channel = new MessageChannel(); 71 channel.port1.onmessage = flush; 72 return () => channel.port2.postMessage(0); 73} 74 75function useSetTimeout() { 76 // Store setTimeout reference so es6-promise will be unaffected by 77 // other code modifying setTimeout (like sinon.useFakeTimers()) 78 const globalSetTimeout = setTimeout; 79 return () => globalSetTimeout(flush, 1); 80} 81 82const queue = new Array(1000); 83function flush() { 84 for (let i = 0; i < len; i+=2) { 85 let callback = queue[i]; 86 let arg = queue[i+1]; 87 88 callback(arg); 89 90 queue[i] = undefined; 91 queue[i+1] = undefined; 92 } 93 94 len = 0; 95} 96 97function attemptVertx() { 98 try { 99 const vertx = Function('return this')().require('vertx'); 100 vertxNext = vertx.runOnLoop || vertx.runOnContext; 101 return useVertxTimer(); 102 } catch(e) { 103 return useSetTimeout(); 104 } 105} 106 107let scheduleFlush; 108// Decide what async method to use to triggering processing of queued callbacks: 109if (isNode) { 110 scheduleFlush = useNextTick(); 111} else if (BrowserMutationObserver) { 112 scheduleFlush = useMutationObserver(); 113} else if (isWorker) { 114 scheduleFlush = useMessageChannel(); 115} else if (browserWindow === undefined && typeof require === 'function') { 116 scheduleFlush = attemptVertx(); 117} else { 118 scheduleFlush = useSetTimeout(); 119} 120