82 lines
2.8 KiB
JavaScript
82 lines
2.8 KiB
JavaScript
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'use strict';
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var global = require('../internals/global');
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var bind = require('../internals/function-bind-context');
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var getOwnPropertyDescriptor = require('../internals/object-get-own-property-descriptor').f;
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var macrotask = require('../internals/task').set;
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var Queue = require('../internals/queue');
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var IS_IOS = require('../internals/engine-is-ios');
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var IS_IOS_PEBBLE = require('../internals/engine-is-ios-pebble');
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var IS_WEBOS_WEBKIT = require('../internals/engine-is-webos-webkit');
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var IS_NODE = require('../internals/engine-is-node');
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var MutationObserver = global.MutationObserver || global.WebKitMutationObserver;
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var document = global.document;
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var process = global.process;
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var Promise = global.Promise;
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// Node.js 11 shows ExperimentalWarning on getting `queueMicrotask`
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var queueMicrotaskDescriptor = getOwnPropertyDescriptor(global, 'queueMicrotask');
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var microtask = queueMicrotaskDescriptor && queueMicrotaskDescriptor.value;
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var notify, toggle, node, promise, then;
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// modern engines have queueMicrotask method
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if (!microtask) {
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var queue = new Queue();
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var flush = function () {
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var parent, fn;
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if (IS_NODE && (parent = process.domain)) parent.exit();
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while (fn = queue.get()) try {
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fn();
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} catch (error) {
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if (queue.head) notify();
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throw error;
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}
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if (parent) parent.enter();
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};
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// browsers with MutationObserver, except iOS - https://github.com/zloirock/core-js/issues/339
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// also except WebOS Webkit https://github.com/zloirock/core-js/issues/898
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if (!IS_IOS && !IS_NODE && !IS_WEBOS_WEBKIT && MutationObserver && document) {
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toggle = true;
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node = document.createTextNode('');
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new MutationObserver(flush).observe(node, { characterData: true });
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notify = function () {
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node.data = toggle = !toggle;
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};
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// environments with maybe non-completely correct, but existent Promise
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} else if (!IS_IOS_PEBBLE && Promise && Promise.resolve) {
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// Promise.resolve without an argument throws an error in LG WebOS 2
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promise = Promise.resolve(undefined);
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// workaround of WebKit ~ iOS Safari 10.1 bug
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promise.constructor = Promise;
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then = bind(promise.then, promise);
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notify = function () {
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then(flush);
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};
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// Node.js without promises
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} else if (IS_NODE) {
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notify = function () {
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process.nextTick(flush);
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};
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// for other environments - macrotask based on:
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// - setImmediate
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// - MessageChannel
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// - window.postMessage
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// - onreadystatechange
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// - setTimeout
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} else {
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// `webpack` dev server bug on IE global methods - use bind(fn, global)
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macrotask = bind(macrotask, global);
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notify = function () {
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macrotask(flush);
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};
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}
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microtask = function (fn) {
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if (!queue.head) notify();
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queue.add(fn);
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};
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}
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module.exports = microtask;
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