TypeScript Conditional Types

Select types dynamically based on boolean type relationships (T extends U ? X : Y).

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Conditional types help describe the relation between the types of inputs and outputs. Formatted like ternary expressions: SomeType extends OtherType ? TrueType : FalseType.

Key Takeaways: TypeScript Conditional Types

Mastering TypeScript Conditional Types helps you write clean and reliable TypeScript code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.

TypeScript Conditional Types Code Example

TypeScript

type IsString<T> = T extends string ? "yes, string" : "no, other";

type A = IsString<string>;
type B = IsString<number>;

const a: A = "yes, string";
const b: B = "no, other";
console.log(a, "|", b);

Output

yes, string | no, other

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TypeScript Conditional Types

💡 Key Takeaways: TypeScript Conditional Types

TypeScript Conditional Types Code Example

Key Takeaways: TypeScript Conditional Types