Provider scope (default, request, transient) in NestJS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the default provider scope in NestJS?

The default provider scope is Singleton. This means one instance of the provider is created and shared across the entire application.

intermediate

Explain the Request provider scope in NestJS.

The Request scope creates a new instance of the provider for each incoming HTTP request. This helps isolate data per request.

intermediate

What does the Transient provider scope do in NestJS?

The Transient scope creates a new instance of the provider every time it is injected, regardless of the request or module.

advanced

How does the Request scope differ from the Transient scope?

The Request scope creates one instance per HTTP request, shared within that request. The Transient scope creates a new instance every time it is injected, even multiple times in the same request.

intermediate

Why would you use Transient scope for a provider?

Use Transient when you want a fresh instance every time to avoid shared state or side effects, like for stateless helpers or utilities.

What scope does NestJS use by default for providers?

A Session

B Singleton

C Transient

D Request

By default, NestJS providers are singletons, meaning one instance is shared across the app.

Which provider scope creates a new instance for each HTTP request?

A Singleton

B Transient

C Global

D Request

The Request scope creates a new provider instance per HTTP request.

If you want a new provider instance every time it is injected, which scope should you use?

A Singleton

B Request

C Transient

D Scoped

Transient scope creates a new instance every time the provider is injected.

Which scope shares the same instance within a single HTTP request but creates new instances for different requests?

A Request

B Singleton

C Transient

D Global

Request scope shares one instance per HTTP request.

Why might you avoid using Singleton scope for stateful providers?

A Because Singleton shares the same instance across all requests, causing shared state issues

B Because Singleton creates multiple instances

C Because Singleton creates new instances per injection

D Because Singleton is slower

Singleton scope shares one instance app-wide, which can cause unwanted shared state for stateful providers.

Describe the differences between default, request, and transient provider scopes in NestJS.

Think about how many instances are created and when.

When would you choose to use the transient scope over the request or default scopes in NestJS?

Consider cases where sharing instances could cause problems.