Learning library
Pilot Course overview

Dependency Injection in TypeScript (Frontend)

Learn dependency injection, inversion of control, and dependency inversion through short, framework-free TypeScript lessons.

View lesson sequence Browse all courses
Before you begin

Course overview

At a glance

Status
Pilot
Published
Updated
Difficulty
Intermediate
Duration
2h
Planned lessons
6

Prerequisites

  • You can read and write basic TypeScript classes, functions, and promises.
  • You understand the role of common browser APIs such as fetch and localStorage.
Purpose

What you will be able to do

This short, self-study course is for software engineers who want to explain and apply dependency injection in TypeScript frontend code. It starts with a small example, then moves to abstractions, control flow, and application wiring.

The public pilot includes the course overview, the first lesson, the glossary, and further reading. The cards below show the planned course order; only published lesson cards open a public lesson page.

  • Explain dependency injection, inversion of control, and dependency inversion with small TypeScript examples.
  • Write constructor injection for browser-facing frontend services without a framework or container.
  • Explain why injection improves testability and demonstrate it with a fake that does not use the network.
  • Identify the composition root and describe where frontend wiring belongs.
Pilot scope

What this pilot includes

Intermediate

Included

  • Course overview, objectives, and prerequisites.
  • The first lesson with its glossary and further reading.
  • Planned six-lesson sequence with publication status for each lesson.

Not included yet

  • The remaining five lesson pages and course completion tracking.
Lessons

Lesson sequence

Take the lessons in order. Published lessons link to their pages; planned lessons are listed below.

  1. What Is a Dependency?

    Published

    Identify a dependency and move the transport choice into the caller.

    15 minutes Beginner dependenciescouplingconstructor injection
    Open lesson

  2. Depend on the Abstraction

    Planned

    Replace concrete details with a small contract so a service can accept different implementations.

    20 minutes Beginner abstractionscontractstest doubles
    Not published

  3. Inversion of Control

    Planned

    Distinguish inversion of control from dependency injection and explain how a caller or framework decides what runs.

    20 minutes Intermediate inversion of controlcontrol flowframeworks
    Not published

  4. The Composition Root

    Planned

    Keep object-graph wiring in one place so application code receives dependencies instead of constructing them.

    20 minutes Intermediate composition rootsobject graphsapplication wiring
    Not published

  5. DI in React

    Planned

    Apply dependency injection in React and distinguish a dependency from a delivery mechanism such as Context.

    20 minutes Intermediate Reactcontextfrontend architecture
    Not published

  6. Scaling the Composition Root

    Planned

    Keep frontend wiring easy to trace as the application grows by making composition decisions explicit and local.

    25 minutes Advanced composition rootsscalingmaintainability
    Not published
Course glossary Further reading

Course citations

AI assistance: This course metadata was reviewed and adapted for the public Astro site with AI assistance.