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