Add packages/common/src/types.ts

packages/common/src/index.ts

@@ -12,4 +12,5 @@ export * from './IUserTeam'
 export * from './ReadonlyRecord'
 export * from './URLFormatter'
 export * from './indexBy'
+export * from './types'
 export * from './without'

packages/common/src/types.ts

@@ -0,0 +1,22 @@
+/**
+ * transform unknown into undefined
+ */
+export type Optional<T> = T extends {} ? T : undefined
+
+export type NonUndefinedPropertyNames<T> = {
+  [K in keyof T]: T[K] extends undefined ? never: K
+}[keyof T]
+
+export type OnlyRequired<T> = Pick<T, NonUndefinedPropertyNames<T>>
+
+export type NonUnknownPropertyNames<T> = {
+  [K in keyof T]: T[K] extends {} ? K : never
+}[keyof T]
+
+export type OnlyDefined<T> = Pick<T, NonUnknownPropertyNames<T>>
+
+/**
+ * Remove types from T that are not assignable to U
+ * https://www.typescriptlang.org/docs/handbook/advanced-types.html
+ */
+export type Filter<T, U> = T extends U ? T : never