Angular 13 was officially released on November 3, 2021. The biggest significance of this release is that it clears out legacy baggage: it completely removes the View Engine code, deprecates IE 11 support, and redesigns the Angular Package Format (APF). For projects already running stably on Ivy, this upgrade brings a smaller dependency footprint and faster compile times.

Complete Removal of View Engine

Angular 12 marked View Engine as deprecated; Angular 13 fully removes the related code:

• Removed the View Engine compilation logic from @angular/compiler
• No longer generates ngfactory and ngsummary files
• TestBed no longer calls compileComponents() (async compilation):

// Angular 13 之前：TestBed 需要 async compileComponents
beforeEach(async () => {
  await TestBed.configureTestingModule({
    declarations: [MyComponent],
  }).compileComponents(); // 需要等待编译
});

// Angular 13：不再需要 await compileComponents（Ivy 是同步的）
beforeEach(() => {
  TestBed.configureTestingModule({
    declarations: [MyComponent],
  });
  // 直接可用，无需 async
});

This makes test code cleaner and test suites run faster.

Dropping IE 11 Support Completely

Angular 13 no longer builds extra polyfills and compatibility code for IE 11:

// angular.json - Angular 13 新建项目不再有 IE 相关配置
// 之前的 browserslist 配置（已移除）：
// IE 11

// .browserslistrc（Angular 13 默认）
last 1 Chrome version
last 1 Firefox version
last 2 Edge major versions
last 2 Safari major versions
last 2 iOS major versions
Firefox ESR

Impact:

• Main bundle size reduced by about 4 KB (IE-related polyfills removed)
• Faster builds (no need to generate ES5-compatible code)
• If you still need to support IE 11, do not upgrade to Angular 13

Redesigning the Angular Package Format (APF)

APF defines how Angular libraries are published to npm. Angular 13 redesigned the APF:

旧 APF（复杂）：
dist/
  esm2015/      ← ES2015 格式
  esm5/         ← ES5 格式（现在不需要了）
  fesm2015/     ← flat ES2015
  fesm5/        ← flat ES5（现在不需要了）
  bundles/      ← UMD 格式

新 APF（简洁）：
dist/
  esm2020/      ← ES2020 格式（现代浏览器）
  fesm2020/     ← flat ES2020
  fesm2015/     ← flat ES2015（旧 Node.js 兼容）

By removing the ES5 artifacts, the published size of libraries was reduced by about 25%.

Simplified Dynamic Component Creation API

Angular 13 simplified the ViewContainerRef.createComponent API:

// Angular 13 之前：需要 ComponentFactoryResolver
const factory = this.resolver.resolveComponentFactory(DynamicComponent);
const componentRef = this.viewContainer.createComponent(factory);

// Angular 13：直接传组件类
const componentRef = this.viewContainer.createComponent(DynamicComponent);
componentRef.instance.data = "some data";

ComponentFactoryResolver still exists (for compatibility) but is deprecated; the new API is recommended.

Inline Fonts Improvements

Angular 13's CLI improved its font-inlining strategy, supporting more Google Fonts formats:

<!-- Angular 13 构建后，字体 CSS 会被内联 -->
<style>
  @font-face {
    font-family: "Inter";
    src: url("https://fonts.gstatic.com/s/inter/...") format("woff2");
    font-display: swap; /* 优化 CLS */
  }
</style>

Automatically adding font-display: swap has a positive impact on the CLS (Cumulative Layout Shift) metric.

Upgrading to Angular 13

ng update @angular/core@13 @angular/cli@13

# 主要自动迁移：
# 1. 移除 TestBed.compileComponents 的 async 包装
# 2. 迁移废弃的 ComponentFactoryResolver 用法
# 3. 更新 tsconfig 中的 target 到 ES2020

Pre-upgrade checklist:

ng update --list
# 确保所有依赖都有 Angular 13 兼容版本

Summary

Angular 13 is a "cleanup" release — it clears out legacy baggage, making the framework lighter and faster. After removing View Engine and IE 11 support, Angular apps' build output shrinks by an average of 10–15%. If none of your users are on IE 11, this upgrade offers excellent value.