Cheat Sheet Tables

TypeScript Power Tools Cheat Sheet

Utility	Purpose	Example
`Partial<T>`	Make all props optional	`Partial<User>`
`Required<T>`	Make all props required	`Required<User>`
`Readonly<T>`	Make all props readonly	`Readonly<User>`
`Pick<T, K>`	Pick some keys	`Pick<User, id' \| 'name'>`
`Omit<T, K>`	Remove some keys	`Omit<User, 'password'>`
`NonNullable<T>`	Remove `null` & `undefined`	`NonNullable<string \| null>`
`Record<K, V>`	Create a key-value map	`Record<string, number>`
`Exclude<T, U>`	Remove types assignable to `U`	`Exclude<'a' \| 'b', 'a'> // 'b'`
`Extract<T, U>`	Keep only types assignable to `U`	`Extract<'a' \| 'b', 'a'> // 'a'`
`ReturnType<F>`	Get return type of a function	`ReturnType<typeof getUser>`
`Parameters<F>`	Get parameter types of a function	`Parameters<typeof getUser>`
`Awaited<T>`	Get resolved type of a Promise	`Awaited<Promise<User>> // User`
`Indexed Access`	Grab part of a type	`UserQuery['profile']`

Combo	Purpose	Example
`Pick<ParentType['nested'], K>`	Extract specific keys from a nested type	`Pick<AccountQuery['user'], 'id' \| 'name'>`
`Omit<ParentType['nested'], K>`	Remove unwanted keys from a nested type	`Omit<AccountQuery['user'], 'password'>`
`Partial<ParentType['nested']>`	Make a nested type partially optional	`Partial<AccountQuery['user']>`
`Required<Pick<T, K>>`	Ensure a subset of props are required	`Required<Pick<User, 'email'>>`
`NonNullable<ParentType['nested']>`	Remove `null` and `undefined` from a nested type	`NonNullable<AccountQuery['user']>`
`ReturnType<typeof fn>` + `Pick<>`	Grab only the needed parts of a function's return	`Pick<ReturnType<typeof getUser>, 'id'>`
`Partial<Pick<T, K>>`	Optional subset for mock/test data	`Partial<Pick<User, 'id' \| 'name'>>`
`Omit<ReturnType<typeof fn>, K>`	Drop noisy keys from function return types	`Omit<ReturnType<typeof getUser>, 'metadata'>`
`Indexed Access` + `Partial<>`	Make part of a deeply nested object optional	`Partial<AccountQuery['user']['stats']>`
`Pick<Extract<T, U>, K>`	Combine filtering + selection	`Pick<Extract<UserRole, 'admin' \| 'moderator'>, 'permissions'>`