88 lines
3.6 KiB
TypeScript
88 lines
3.6 KiB
TypeScript
// Safari 6 and 6.1 for desktop, iPad, and iPhone are the only browsers that
|
|
// have WebKitMutationObserver but not un-prefixed MutationObserver.
|
|
// Must use `global` or `self` instead of `window` to work in both frames and web
|
|
// workers. `global` is a provision of Browserify, Mr, Mrs, or Mop.
|
|
|
|
/* globals self */
|
|
const scope = typeof global !== 'undefined' ? global : self
|
|
const BrowserMutationObserver =
|
|
(scope as any).MutationObserver || (scope as any).WebKitMutationObserver
|
|
|
|
export function makeRequestCallFromTimer(callback: () => void) {
|
|
return function requestCall() {
|
|
// We dispatch a timeout with a specified delay of 0 for engines that
|
|
// can reliably accommodate that request. This will usually be snapped
|
|
// to a 4 milisecond delay, but once we're flushing, there's no delay
|
|
// between events.
|
|
const timeoutHandle = setTimeout(handleTimer, 0)
|
|
// However, since this timer gets frequently dropped in Firefox
|
|
// workers, we enlist an interval handle that will try to fire
|
|
// an event 20 times per second until it succeeds.
|
|
const intervalHandle = setInterval(handleTimer, 50)
|
|
|
|
function handleTimer() {
|
|
// Whichever timer succeeds will cancel both timers and
|
|
// execute the callback.
|
|
clearTimeout(timeoutHandle)
|
|
clearInterval(intervalHandle)
|
|
callback()
|
|
}
|
|
}
|
|
}
|
|
|
|
// To request a high priority event, we induce a mutation observer by toggling
|
|
// the text of a text node between "1" and "-1".
|
|
export function makeRequestCallFromMutationObserver(callback: () => void) {
|
|
let toggle = 1
|
|
const observer = new BrowserMutationObserver(callback)
|
|
const node = document.createTextNode('')
|
|
observer.observe(node, { characterData: true })
|
|
return function requestCall() {
|
|
toggle = -toggle
|
|
;(node as any).data = toggle
|
|
}
|
|
}
|
|
|
|
export const makeRequestCall =
|
|
typeof BrowserMutationObserver === 'function'
|
|
? // MutationObservers are desirable because they have high priority and work
|
|
// reliably everywhere they are implemented.
|
|
// They are implemented in all modern browsers.
|
|
//
|
|
// - Android 4-4.3
|
|
// - Chrome 26-34
|
|
// - Firefox 14-29
|
|
// - Internet Explorer 11
|
|
// - iPad Safari 6-7.1
|
|
// - iPhone Safari 7-7.1
|
|
// - Safari 6-7
|
|
makeRequestCallFromMutationObserver
|
|
: // MessageChannels are desirable because they give direct access to the HTML
|
|
// task queue, are implemented in Internet Explorer 10, Safari 5.0-1, and Opera
|
|
// 11-12, and in web workers in many engines.
|
|
// Although message channels yield to any queued rendering and IO tasks, they
|
|
// would be better than imposing the 4ms delay of timers.
|
|
// However, they do not work reliably in Internet Explorer or Safari.
|
|
|
|
// Internet Explorer 10 is the only browser that has setImmediate but does
|
|
// not have MutationObservers.
|
|
// Although setImmediate yields to the browser's renderer, it would be
|
|
// preferrable to falling back to setTimeout since it does not have
|
|
// the minimum 4ms penalty.
|
|
// Unfortunately there appears to be a bug in Internet Explorer 10 Mobile (and
|
|
// Desktop to a lesser extent) that renders both setImmediate and
|
|
// MessageChannel useless for the purposes of ASAP.
|
|
// https://github.com/kriskowal/q/issues/396
|
|
|
|
// Timers are implemented universally.
|
|
// We fall back to timers in workers in most engines, and in foreground
|
|
// contexts in the following browsers.
|
|
// However, note that even this simple case requires nuances to operate in a
|
|
// broad spectrum of browsers.
|
|
//
|
|
// - Firefox 3-13
|
|
// - Internet Explorer 6-9
|
|
// - iPad Safari 4.3
|
|
// - Lynx 2.8.7
|
|
makeRequestCallFromTimer
|