Type-safe API response handling in Typescript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does type-safe API response handling mean in TypeScript?

It means ensuring that the data received from an API matches expected types, so your program can safely use the data without runtime errors.

beginner

How can you define the expected shape of an API response in TypeScript?

By creating an interface or type that describes the structure and types of the response data.

beginner

What is the purpose of using fetch with async/await in API calls?

It allows you to write asynchronous code that waits for the API response before continuing, making the code easier to read and handle errors.

intermediate

Why should you validate or check API response data even when using TypeScript types?

Because TypeScript types only check code at compile time, but API data comes from outside and might not match the expected types at runtime.

intermediate

What is a simple way to ensure type safety when parsing JSON from an API?

Use a function that checks the presence and type of required fields before using the data, or use libraries like zod or io-ts for runtime validation.

Which TypeScript feature helps define the expected structure of API response data?

A class

B var

C interface

D function

The interface keyword defines the shape and types of an object, perfect for API responses.

Why is it important to check API response data at runtime even with TypeScript types?

A Because runtime checks slow down the program

B Because TypeScript automatically fixes data errors

C Because API data is always correct

D Because TypeScript types only check during coding, not actual data received

TypeScript types help during development but cannot guarantee the external API sends correct data.

What does async/await do in API calls?

A Makes code wait for the API response before continuing

B Makes the API call synchronous

C Automatically validates API data

D Prevents API calls

async/await lets you write code that pauses until the API responds, making it easier to handle results.

Which library can help with runtime validation of API responses in TypeScript?

A zod

B lodash

C express

D react

zod is a popular library to check data shapes at runtime in TypeScript.

What is the first step to handle an API response type-safely?

A Call the API without checking

B Define the expected response type with an interface or type

C Ignore the response data

D Use <code>any</code> type for the response

Defining the expected type helps TypeScript understand what data to expect and catch mistakes early.

Explain how you would safely handle an API response in TypeScript from fetching data to using it.

Think about the steps from calling the API to using the data in your program.

Why is runtime validation important even if you use TypeScript types for API responses?

Consider the difference between compile-time and runtime.