arturovt fc6a7eea68 fix(zone.js): allow draining microtasks in Promise.then (through flag)
These changes are essentially the same as those introduced in
angular#45273, but they include backward compatibility
for applications that explicitly rely on the order in which microtasks are drained.

This is critically important for our code and other third-party code, which is
beyond our control, to work properly. If a microtask is scheduled within an event
listener to be executed "later", it should indeed be executed later and not synchronously,
as this would break the expected flow of code execution.

The simple code that reproduces the behavior that exists now:

```ts
Zone.current.fork({name: 'child'}).run(() => {
  const div = document.createElement('div');
  div.style.height = '200px';
  div.style.width = '200px';
  div.style.backgroundColor = 'red';
  document.body.appendChild(div);

  function listener() {
    Promise.resolve().then(() => {
      div.style.height = '400px';
    });
  }

  div.addEventListener('fakeEvent', listener);
  div.dispatchEvent(new Event('fakeEvent'));
  console.log(div.getBoundingClientRect().height); // 400
});
```

The code above logs 400 as the height, but it should actually log 200 because the
height is updated in a microtask within the event listener.

When using Angular with microfrontend applications, especially when other apps might be
using React, zone.js can disrupt the classical order of operations. For example, when using a
`react-component/trigger`, it schedules a microtask within an event listener using
`Promise.resolve().then(...)` to determine whether the event needs to be re-dispatched.
The event is re-dispatched when the layout has changed, which is why a microtask is used.

With this change, we introduce a global configuration flag,
`__zone_symbol__enable_native_microtask_draining`, to allow consumers to enable
microtask draining within a browser microtask.

This flag is necessary to prevent any breaking changes resulting from this modification.
The previous attempt to address this issue caused a significant number of failures in g3.
Therefore, we are hiding that fix behind the configuration flag.

Closes angular#44446
Closes angular#55590
Closes angular#51328
2026-04-15 10:31:28 -04:00
2026-04-10 16:45:32 +03:00
2025-12-08 10:21:59 -08:00
…
…
2026-02-17 08:23:59 -08:00
2025-11-06 10:03:05 -08:00
2025-11-06 10:03:05 -08:00
2026-01-07 12:28:34 -05:00

Angular - The modern web developer's platform

angular-logo
Angular is a development platform for building mobile and desktop web applications
using TypeScript/JavaScript and other languages.

angular.dev

Contributing Guidelines · Submit an Issue · Blog

Angular on npm


Documentation

Get started with Angular, learn the fundamentals and explore advanced topics on our documentation website.

Advanced

Local Development

To contribute to the Angular Docs, check out the Angular.dev README

Development Setup

Prerequisites

Setting Up a Project

Install the Angular CLI globally:

npm install -g @angular/cli

Create workspace:

ng new [PROJECT NAME]

Run the application:

cd [PROJECT NAME]
ng serve

Angular is cross-platform, fast, scalable, has incredible tooling, and is loved by millions.

Quickstart

Get started in 5 minutes.

Ecosystem

angular ecosystem logos

Changelog

Learn about the latest improvements.

Upgrading

Check out our upgrade guide to find out the best way to upgrade your project.

Contributing

Contributing Guidelines

Read through our contributing guidelines to learn about our submission process, coding rules, and more.

Want to Help?

Want to report a bug, contribute some code, or improve the documentation? Excellent! Read up on our guidelines for contributing and then check out one of our issues labeled as help wanted or good first issue.

Code of Conduct

Help us keep Angular open and inclusive. Please read and follow our Code of Conduct.

Community

Join the conversation and help the community.

Love Angular badge

Love Angular? Give our repo a star ⭐ ⬆️.

S
Description
Generates Angular code and provides architectural guidance. Trigger when creating projects, components, services, or HTTP communication, or for best practices…
Readme MIT 1 GiB
Languages
TypeScript 81.7%
JavaScript 12.8%
HTML 2%
Starlark 1.8%
CSS 1%
Other 0.7%