TypeScript 7 reference · Utility Types

TypeScript Uppercase<StringType> Utility Type

Turn a string literal type into upper case at the type level: Uppercase<'get'> is 'GET'.

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Syntax

Uppercase<StringType>

Parameter	Description
`StringType`	A string literal type (or union).

The upper-cased literal type.

HTTP methodsTry it yourself

type Method = "get" | "post";
type HttpMethod = Uppercase<Method>; // "GET" | "POST"
const m: HttpMethod = "POST";
console.log(m);

Output

POST

With template literal typesTry it yourself

type Env = "dev" | "prod";
type EnvVar = `APP_${Uppercase<Env>}_URL`;
const v: EnvVar = "APP_PROD_URL";
console.log(v);

Output

APP_PROD_URL

Version	Change
TypeScript 4.1	Added

Capitalize<StringType> · Upper-case the first character of a string literal type: Capitalize<'click'> is 'Click'. Used to build names like onClick.
template literal types · Build string literal types with template syntax: `on${string}` or combinations of unions like `${Size}-${Color}`.
TypeScript Utility Types · tutorial