# Create an Angular Micro Frontend

Prerequisites

A working instance of Entando.

Tested Versions

node v13.8.0 → We suggest using nvm (opens new window) to handle node installations.

# Create Angular App

Install Angular CLI.

npm install -g @angular/cli

Generate a new angular application.

ng new angular-widget

Choose the following options:

? Would you like to add Angular routing? No
? Which stylesheet format would you like to use? CSS

Serve the application.

cd angular-widget

ng serve

This is the expected output:

angular-widget
├── e2e
│   └── src
│       ├── app.e2e-spec.ts
│       └── app.po.ts
│
├── node_modules
├── src
│   ├── app
│   │   ├── app.component.css
│   │   ├── app.component.html
│   │   ├── app.component.spec.ts
│   │   ├── app.component.ts
│   │   └── app.module.ts
│   │
│   ├── assets
│   │   └── .gitkeep
│   │
│   ├── environment
│   │   ├── environment.prod.ts
│   │   └── environment.ts
│   │
│   ├── favicon.ico
│   ├── index.html
│   ├── main.ts
│   ├── polyfills.ts
│   ├── styles.css
│   └── test.ts
│
├── .editorconfig
├── .gitignore
├── angular.json
├── browserlist
├── karma.conf.js
├── package.json
├── README.md
├── tsconfig.app.json
├── tsconfig.json
├── tsconfig.spec.json
└── tslint.json

# Convert to Custom Element

Next, let's convert our Angular app into a custom element. We'll use Angular elements (opens new window) to transform components into custom elements.

ng add @angular/elements

WARNING

Install the Angular elements package using ng add, not with npm install as it runs additional steps behind the scenes like adding the document-register-element polyfill.

TIP

Angular elements are Angular components packaged as custom elements (also called Web Components), a web standard for defining new HTML elements in a framework-agnostic way. (opens new window)

Open angular-widget/src/app/app.module.ts.

Here's what the initial file looks like:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppComponent } from './app.component';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Replace the entire file with:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule, Injector } from '@angular/core';
import { createCustomElement } from '@angular/elements';
import { AppComponent } from './app.component';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule
  ],
  providers: [],
  entryComponents: [AppComponent]
})
export class AppModule {
  constructor(private injector: Injector) {}

  ngDoBootstrap() {
    const el = createCustomElement(AppComponent, { injector: this.injector });
    customElements.define('angular-widget', el);
  }
}

In the initial file, AppModule is bootstrapped directly during application launch.
In the updated file, we booststrap our custom element using the ngDoBootstrap() method (opens new window).

Custom Elements

Must contain a hyphen - in the name. (opens new window):
Cannot be a single word.
Should follow kebab-case for naming convention.

# Test Micro Frontend

Now, let's check our custom element to see if it's working.

Open angular-widget/src/index.html.

In the <body>, replace <app-root></app-root> with your custom element <angular-widget />.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>AngularWidget</title>
  <base href="/">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="icon" type="image/x-icon" href="favicon.ico">
</head>
<body>
  <angular-widget />
</body>
</html>

Congratulations!

You’re now running Angular in a micro frontend.

# Build It

From the project root, type:

ng build --prod --outputHashing=none

This will generate an angular-widget/dist directory.

If we assume browser support for ES6 (ECMAScript 2015) (opens new window), we can focus on the following JavaScript files to publish our app:

main-es2015.js
polyfills-es2015.js
runtime-es2015.js

Generated Build Files

--outputHashing=none generates files without hashes so we can deploy new versions of the micro frontend without having to reconfigure our widget in Entando to point to the newly built files.

If you want to use file names with content hashes to avoid potential caching issues in your browser, you can update the Custom UI field of your widget after building new versions of your micro frontend. Widget configuration is covered in the next section.

# Host Micro Frontend

Now we're ready to host our micro frontend in Entando.

# Create Public Folder

Navigate to Entando App Builder in your browser.
Click Administration at the lower left hand side of the screen.
Click the File Browser tab.
Click the public folder.
Click Create Folder.
Enter angular-widget
Click Save.
Click angular-widget.
Click 'Upload Files`.
Upload the following files from angular-widget/dist/angular-widget:

main-es2015.js
polyfills-es2015.js
runtime-es2015.js

Additional Deployment Options

Install the micro frontend from a bundle in the Entando Component Repository.
Add the micro frontend to Entando App Builder.
Load the micro frontend from an API.

Go to Components > Micro frontends & Widgets in the Entando App Builder.
Click Add at the lower right.

Enter the following:

Code: angular_widget → note: dashes are not allowed
Title: Angular Widget → for both English and Italian languages
Group: Free Access
Custom UI:

<#assign wp=JspTaglibs[ "/aps-core"]>
<script async src="<@wp.resourceURL />angular-widget/main-es2015.js"></script>
<script async src="<@wp.resourceURL />angular-widget/polyfills-es2015.js"></script>
<script async src="<@wp.resourceURL />angular-widget/runtime-es2015.js"></script>

<angular-widget />

Click Save.

TIP

<#assign wp=JspTaglibs[ "/aps-core"]> gives you access to the @wp object where you can use environment variables like resourceURL.

# See It in Action

Let's see the Angular micro frontend in action on our page.

# Add Page

Note

If you've already configured your home page:

Next to the Home folder, under Actions, click Configure.
Skip to the Add Widget section.

Let's add our widget to the Home page.

Go to Pages → Management
Next to the Home folder, under Actions, click Edit.
Next to Page Template select Service Page.
Click Save and Configure.

In the Search field in right-hand sidebar, enter Angular Widget.
Drag and drop Angular Widget into the Sample Frame in the main body of the page.
Click Publish.
At the upper right, click Go to Homepage.

Angular Micro Frontend