TypeScript in Depth · Generics · Lesson 7 of 16

Why Generics?

Concept

Why Generics?

Generics let a function or type work with any type while still preserving type safety, instead of writing duplicate code per type.

By the end of this lesson

Explain the core idea behind Why Generics?.
Predict output before running a change.
Test one realistic and one unusual input.
Use the result to make the next decision.

How to study this page

1. Read one concept.
2. Change the example.
3. Run, compare, and explain.
4. Complete the challenge below.

ExampleRunnable

function identity<T>(value: T): T {
  return value;
}

Try it Yourself »

Self-check before continuing

Without looking at the example, describe what changes when you modify one input in Why Generics?. Then reopen the editor and prove your explanation with a small test.

You are ready to continue when you can predict, test, and explain the result.

Your turn

Call the identity function with a number, then with a string.

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Console

Output will appear here...