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# 10 must-know design patterns for JS Devs

Are you using TypeScript like a Ferrari to deliver pizza? Master these ten essential Vanilla JavaScript design patterns to transform messy scripts into highly scalable applications.

- **Speakers:** Erick Wendel
- **Event:** World Congress 2023
- **Published:** September 27, 2023
- **Duration:** 28:13
- **URL:** https://www.wearedevelopers.com/videos/695-10-must-know-design-patterns-for-js-devs

## Summary

Many developers struggle with monolithic, untested JavaScript files plagued by global states and tangled logic. By drawing inspiration from strongly-typed languages and applying SOLID principles to Vanilla JS, it is possible to transform messy scripts into scalable applications. Splitting code into distinct Service, View, and Controller layers establishes a robust foundation that separates business logic from UI rendering, making the codebase highly maintainable.\n\nImplementing classical design patterns directly in ECMAScript unlocks massive architectural benefits without needing complex bundlers. The Abstract Factory pattern enables universal apps that share core logic but render uniquely across web browsers and command-line interfaces. For complex component creation, Builder and Fluent Builder patterns provide a clean, step-by-step API. Testing scales significantly better when using a Test Data Builder to centralize mock states, rather than copy-pasting configurations. Furthermore, the Observer pattern facilitates decoupled event-driven behaviors—such as logging or analytics—operating on a "don't call me, I'll call you" subscription model.\n\nModern JavaScript features can replace heavy external libraries when properly leveraged. Decorators dynamically inject performance tracking or error handling into existing functions without altering the underlying logic. For severe performance bottlenecks, combining the Iterator protocol with data streams and the yield keyword allows the frontend to consume gigabytes of data on demand, eliminating white screens. Ultimately, mastering these foundational Vanilla JS patterns prevents developers from blindly relying on supersets like TypeScript, which can be like "riding a Ferrari to delivery pizza" if the underlying language mechanics are misunderstood.

**Keywords:** vanilla javascript design patterns, single responsibility principle, layered application architecture, abstract factory pattern, cross-platform rendering, fluent builder implementation, test data builder pattern, observer pattern architecture, javascript decorator injection, iterator protocol streams, frontend data processing, generator yield keyword, ecmascript private fields, typescript vs vanilla javascript, ui state management

## Chapters

1. **Identifying problems in single-file JavaScript applications** (00:00) — Global state and lack of folder structure create hard-to-maintain legacy codebases.
1. **Organizing code with single responsibility and factory patterns** (04:35) — Applying the single responsibility principle splits functionality into manageable views, controllers, and services.
1. **Building universal applications with the abstract factory pattern** (07:44) — Standardizing contracts shares core logic between web and terminal interfaces.
1. **Structuring complex components with builder and fluent APIs** (11:01) — The builder pattern creates modular UI components and flexible queries without massive configuration files.
1. **Reusing state configuration with the test data builder** (13:14) — The test data builder standardizes mock setups and HTTP responses to avoid copy-pasting scenarios.
1. **Managing application events using the observer design pattern** (15:27) — The observer pattern decouples event subscriptions and notifications for analytics and logging integrations.
1. **Injecting behaviors dynamically using the decorator pattern** (17:21) — Decorator functions extend capabilities like performance tracking without modifying the underlying implementation.
1. **Processing large payloads efficiently with streams and generators** (20:55) — Consuming data on demand using the yield keyword prevents UI blocking during large payloads.
1. **Exploring ECMAScript private fields and TypeScript adoption trade-offs** (23:44) — Audience questions cover private class fields in modern JavaScript and the necessity of TypeScript.

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