How to Create an Angular Modular Plugin for Beginners

Angular Plugins: What are They? 

A plugin in Angular is like a tool you can add to your app to improve it. Think of it as a LEGO piece. You can snap it on or off to add new features without breaking the rest of your creation.

These plugins follow a plugin architecture, which helps keep your app neat and organized. This means you can add or replace features without changing the main parts of your app (called the core application code).

Examples of Angular Plugins

Here are some popular types of plugins you might use in an Angular app:

• Authentication Plugin: Adds a login system to your app (e.g., OAuth2 integration).
• Charts and Graphs Plugin: Displays data in cool visual formats like bar charts.
• File Upload Plugin: Makes it easy to upload files, like images or PDFs.
• Translation Plugin: Helps your app support multiple languages for users worldwide.
• Custom Theme Plugin: Changes the look and feel of your app.

These plugins save time and effort because you don’t need to write everything from scratch.

Why Should You Use Angular Plugins?

Using Angular plugins offers many benefits for developers. Here's why they are a great choice:

• Flexibility: Add or remove features without changing the main code.
• Saves Time: Use ready-made tools instead of building from scratch.
• Future-Proof: Easily upgrade your app with new features.
• Reusability: Use the same plugin in multiple projects.
• Improved Performance: Many plugins are optimized for speed and efficiency.
• Keeps Apps Organized: Plugins help keep your code clean and modular.

‍How to Develop a Modular Plug-in for Angular 4

‍Interested in developing a modular plug-in for Angular 4? Follow these steps: 

‍Create a Small Angular Application

1. Install Angular CLI:

Install angular-cli by running → npm install @angular/cli -g

2. Create an Angular project:

Run ng new MyLibrary to create a project, move to the directory through cd MyLibrary, and run ng serve to start the server. Browse to localhost:4200 to see the welcome page.

3. Let's Create a Small Greeting Application:

‍Create a module ng generate module modules/greeting, it will create a file with directories. Use: src/app/modules/greeting/greeting.module.ts

After that create a component, and run ng generate component modules/greeting. Use: run ng generate component modules/greeting 

→ it will create four files in modules/greeting. Replace content from modules/greeting/greeting.component.html with:

“Greetings, My Lord!”

Add CSS in modules/greeting/greeting.component.css:
h1{
color: green;
text-align: center;
padding: 10px;
border: 1px solid green;
}

This is how it will look in the code: 

4. Export Our Component from Our Module

Ensure that an application which imports our GreetingModule will be able to use our GreetingComponent. Without exports, other applications cannot use our component.

This is how you can export your component from your module:

import { NgModule } from ‘@angular/core’;
import { CommonModule } from ‘@angular/common’;
import { GreetingComponent } from ‘./greeting.component’;

@NgModule({
imports: [
CommonModule
],
declarations: [GreetingComponent],
exports: [GreetingComponent] <——– Export component
})
export class GreetingModule { }

This is how it will look in the code: 

5. Import GreetingModule into AppModule and Run Application

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

import { AppComponent } from ‘./app.component’;

// Import our module
import { GreetingModule } from ‘./modules/greeting/greeting.module’;

@NgModule({
declarations: [
AppComponent
],
imports: [
BrowserModule,
GreetingModule <—– import it into ngModule
],
providers: [],
bootstrap: [AppComponent] })
export class AppModule { }

This is how it will look in the code: 

Now run ng serve and look at localhost:4200.

Make Your App into a Plug-in

1. Ng-packagr

ng-packagr is a node library that can compile and package a TypeScript library to Angular Package Format.

Run npm install ng-packagr –save-dev OR npm install ng-packagr, from the root of your application. As ng-packagr docs, we need to add two files:

1. Ng-package.json
2. Public_api.ts

Ng-package.json configures our ng-packagr, and tells it where to find public_api.ts file. We will use this to export feature modules of our component library.
In ng-package.json:
{
“$schema”: “./node_modules/ng-packagr/ng- package.schema.json”,
“lib”: { “entryFile”: “public_api.ts” }
}

In public_api.ts, export GreetingModule:

export * from ‘./src/app/modules/greeting/greeting.module’

Now we will add packagr script to our package.json file. We can use it to tell ng-packagr to package up our library according to configuration of ng-package.json.

Switch private: true in package.json to private: false so you can publish your library when you need to. Use:

“scripts”: {
….
“packagr”: “ng-packagr -p ng-package.json” <—–
}
“private”: false <—–

2. Create Package:

Run cmd npm run packagr. After completing this process, it will create a folder dist in the project root.

Locally used for development:
Move into dist folder which you just created. Run cmd npm pack, it will create a file “MyLibrary-0.0.0.tgz”.

Move into another project root directory in which you want to use your library, and run: npm install ../relative-path/dist/MyLibrary-0.0.0.tgz

Now import your GreetingModule in the AppModule of the project. You can add a tag in any component.html.

3. Publish Plug-in to NPM:

Once you login to your npm account with npm login, you can publish your component library with npm publish dist.

Just be sure that you have a unique package name (Hint: MyLibrary may be taken). Once published, you can install your component library from npm with npm install my-component-library.

Benefits of Using External Plugins in Angular Applications

Using external plugins in Angular can make your apps more powerful and easier to manage. Here’s how they help:

Simplifies App Development with Ready-Made Tools

Instead of building everything from scratch, you can use plugin libraries that are already tested and optimized. These plugins act as shortcuts, saving you time and effort while still delivering professional results.

For example, you can add authentication, file upload, or chart tools to your app instantly.

Improves Performance with Lazy Loading

Plugins often support the lazy loading feature, which means parts of your app only load when needed. This speeds up your app and uses fewer resources. For instance, a plugin for charts won’t load until the user views a graph.

This makes your app faster and more efficient.

Promotes Code Reusability

With plugins, you can reuse library code across multiple projects. For example, if you create a custom plugin for a feature like a contact form, you can use it in any app without rewriting the code.

This saves time and ensures consistency.

Simplifies Maintenance with Modular Design

Plugins help break down your app into smaller parts, such as lazy loaded modules. This keeps your app organized and makes fixing bugs or adding new features easier.

Developers can work on a separate file without affecting the rest of the app.

Reduces Complexity with Clear Plugin Configuration

Plugins come with built-in plugin configuration, so you don’t have to worry about setting things up from scratch.

This reduces errors and ensures everything works smoothly, even when combining multiple plugin components or other plugins.

Optimized for Advanced Features Like Server-Side Rendering

Some plugins are designed to work with advanced techniques like server-side rendering. This improves your app’s performance on slower networks.

It also enhances SEO by making content visible to search engines.

Best Practices for Plugin Development 

Developing a plugin system requires careful planning and smart practices. Follow these best practices to create reliable plugins for your Angular applications:

1. Break Plugins into Smaller Parts

Divide your plugin into smaller external modules or components. 

This makes it easier to manage, reuse, and debug. For example, instead of having one big plugin, create a new module for each specific feature, like a chart or login module. Smaller parts are more flexible and easier to test.

2. Test Every Plugin Thoroughly

Run unit, integration, and end-to-end tests on your plugin.

This ensures that the code generated works as expected in different scenarios. Testing prevents bugs from affecting your main app or other projects using your plugin. Tools like Jasmine and Karma can help with automated testing.

Read More: What Skills to Look For When Hiring Angular Developers

3. Provide Clear Documentation

Write step-by-step instructions for:

• Installation
• Plugin configuration
• Usage

Include examples of how to connect your plugin to the main app or a shared library. Clear guides help developers quickly integrate your plugin into their web applications without confusion.

4. Optimize Plugin Performance

Use the lazy load feature to improve speed by loading parts of your plugin only when needed.

For example, load a large charting plugin only when the user views a chart. Optimize other areas like bundle file path and server-side rendering for maximum efficiency.

5. Keep Plugin Code Modular and Independent

Ensure that your plugin relies only on necessary external sources. 

It should not interfere with the source code of the main app. Use Angular’s private routers and services to keep things isolated. This keeps your plugin self-contained and easy to integrate with other plugin systems.

Final Verdict

Creating an Angular Modular Plugin can be simple with the right steps and practices. By following this guide, you can build reusable, shareable plugins that enhance your Angular projects. Whether it's adding login systems, charts, or translations, plugins simplify app development and improve performance.

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