1 1
/* @flow */
2 -
/* globals MessageChannel */
2 +
/* globals MutationObserver */
3 3 4 4
import { noop } from 'shared/util'
5 5
import { handleError } from './error'
6 -
import { isIOS, isNative } from './env'
6 +
import { isIE, isIOS, isNative } from './env'
7 7 8 8
const callbacks = []
9 9
let pending = false
@@ -17,76 +17,67 @@ function flushCallbacks () {
17 17
}
18 18
}
19 19 20 -
// Here we have async deferring wrappers using both microtasks and (macro) tasks.
21 -
// In < 2.4 we used microtasks everywhere, but there are some scenarios where
22 -
// microtasks have too high a priority and fire in between supposedly
23 -
// sequential events (e.g. #4521, #6690) or even between bubbling of the same
24 -
// event (#6566). However, using (macro) tasks everywhere also has subtle problems
25 -
// when state is changed right before repaint (e.g. #6813, out-in transitions).
26 -
// Here we use microtask by default, but expose a way to force (macro) task when
27 -
// needed (e.g. in event handlers attached by v-on).
28 -
let microTimerFunc
29 -
let macroTimerFunc
30 -
let useMacroTask = false
20 +
// Here we have async deferring wrappers using microtasks.
21 +
// In 2.5 we used (macro) tasks (in combination with microtasks).
22 +
// However, it has subtle problems when state is changed right before repaint
23 +
// (e.g. #6813, out-in transitions).
24 +
// Also, using (macro) tasks in event handler would cause some weird behaviors
25 +
// that cannot be circumvented (e.g. #7109, #7153, #7546, #7834, #8109).
26 +
// So we now use microtasks everywhere, again.
27 +
// A major drawback of this tradeoff is that there are some scenarios
28 +
// where microtasks have too high a priority and fire in between supposedly
29 +
// sequential events (e.g. #4521, #6690, which have workarounds)
30 +
// or even between bubbling of the same event (#6566).
31 +
let timerFunc
31 32 32 -
// Determine (macro) task defer implementation.
33 -
// Technically setImmediate should be the ideal choice, but it's only available
34 -
// in IE. The only polyfill that consistently queues the callback after all DOM
35 -
// events triggered in the same loop is by using MessageChannel.
36 -
/* istanbul ignore if */
37 -
if (typeof setImmediate !== 'undefined' && isNative(setImmediate)) {
38 -
macroTimerFunc = () => {
39 -
setImmediate(flushCallbacks)
40 -
}
41 -
} else if (typeof MessageChannel !== 'undefined' && (
42 -
isNative(MessageChannel) ||
43 -
// PhantomJS
44 -
MessageChannel.toString() === '[object MessageChannelConstructor]'
45 -
)) {
46 -
const channel = new MessageChannel()
47 -
const port = channel.port2
48 -
channel.port1.onmessage = flushCallbacks
49 -
macroTimerFunc = () => {
50 -
port.postMessage(1)
51 -
}
52 -
} else {
53 -
/* istanbul ignore next */
54 -
macroTimerFunc = () => {
55 -
setTimeout(flushCallbacks, 0)
56 -
}
57 -
}
58 - 59 -
// Determine microtask defer implementation.
33 +
// The nextTick behavior leverages the microtask queue, which can be accessed
34 +
// via either native Promise.then or MutationObserver.
35 +
// MutationObserver has wider support, however it is seriously bugged in
36 +
// UIWebView in iOS >= 9.3.3 when triggered in touch event handlers. It
37 +
// completely stops working after triggering a few times... so, if native
38 +
// Promise is available, we will use it:
60 39
/* istanbul ignore next, $flow-disable-line */
61 40
if (typeof Promise !== 'undefined' && isNative(Promise)) {
62 41
const p = Promise.resolve()
63 -
microTimerFunc = () => {
42 +
timerFunc = () => {
64 43
p.then(flushCallbacks)
65 -
// in problematic UIWebViews, Promise.then doesn't completely break, but
44 +
// In problematic UIWebViews, Promise.then doesn't completely break, but
66 45
// it can get stuck in a weird state where callbacks are pushed into the
67 46
// microtask queue but the queue isn't being flushed, until the browser
68 47
// needs to do some other work, e.g. handle a timer. Therefore we can
69 48
// "force" the microtask queue to be flushed by adding an empty timer.
70 49
if (isIOS) setTimeout(noop)
71 50
}
72 -
} else {
73 -
// fallback to macro
74 -
microTimerFunc = macroTimerFunc
75 -
}
76 - 77 -
/**
78 -
* Wrap a function so that if any code inside triggers state change,
79 -
* the changes are queued using a (macro) task instead of a microtask.
80 -
*/
81 -
export function withMacroTask (fn: Function): Function {
82 -
return fn._withTask || (fn._withTask = function () {
83 -
useMacroTask = true
84 -
try {
85 -
return fn.apply(null, arguments)
86 -
} finally {
87 -
useMacroTask = false
88 -
}
51 +
} else if (!isIE && typeof MutationObserver !== 'undefined' && (
52 +
isNative(MutationObserver) ||
53 +
// PhantomJS and iOS 7.x
54 +
MutationObserver.toString() === '[object MutationObserverConstructor]'
55 +
)) {
56 +
// Use MutationObserver where native Promise is not available,
57 +
// e.g. PhantomJS, iOS7, Android 4.4
58 +
// (#6466 MutationObserver is unreliable in IE11)
59 +
let counter = 1
60 +
const observer = new MutationObserver(flushCallbacks)
61 +
const textNode = document.createTextNode(String(counter))
62 +
observer.observe(textNode, {
63 +
characterData: true
89 64
})
65 +
timerFunc = () => {
66 +
counter = (counter + 1) % 2
67 +
textNode.data = String(counter)
68 +
}
69 +
} else if (typeof setImmediate !== 'undefined' && isNative(setImmediate)) {
70 +
// Fallback to setImmediate.
71 +
// Techinically it leverages the (macro) task queue,
72 +
// but it is still a better choice than setTimeout.
73 +
timerFunc = () => {
74 +
setImmediate(flushCallbacks)
75 +
}
76 +
} else {
77 +
// Fallback to setTimeout.
78 +
timerFunc = () => {
79 +
setTimeout(flushCallbacks, 0)
80 +
}
90 81
}
91 82 92 83
export function nextTick (cb?: Function, ctx?: Object) {
@@ -104,11 +95,7 @@ export function nextTick (cb?: Function, ctx?: Object) {
104 95
})
105 96
if (!pending) {
106 97
pending = true
107 -
if (useMacroTask) {
108 -
macroTimerFunc()
109 -
} else {
110 -
microTimerFunc()
111 -
}
98 +
timerFunc()
112 99
}
113 100
// $flow-disable-line
114 101
if (!cb && typeof Promise !== 'undefined') {
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