Personal collection of assorted TypeScript utility types
StrictEqual<A, B>IfAny<T, ThenType, ElseType>IfUnknown<T, ThenType, ElseType>IfNever<T, ThenType, ElseType>ParseArray<A, B>SetKeyType<BaseType, Key, NewType, AsOptional>ReplaceKeyType<BaseType, Key, NewType, AsOptional>
$ npm install @papb/assorted-ts-utils
import {
StrictEqual,
ReplaceKeyType,
ParseArray,
ReplaceAllTypeOccurrences,
IfAny,
IfNever
} from '@papb/assorted-ts-utils';
import {
tsAssertTrue,
tsAssertTypeAcceptsValue,
tsAssertTypesExactlyEqual,
tsAssertExtends
} from '@papb/assorted-ts-utils/assert';
type T1 = StrictEqual<{ a: 1 }, { a: 1 }>;
//=> type T1 = true
type T2 = StrictEqual<{ a: 1 }, { a: 1; b: undefined }>;
//=> type T2 = false
type T3 = ReplaceKeyType<
{ foo: string; bar: number },
'bar',
Date,
true
>;
//=> type T3 = { foo: string; bar?: Date }
type T4 = StrictEqual<
ParseArray<readonly [string, Date, number, null, ...boolean[]]>,
{
isReadonly: true;
first: string;
last: boolean;
minLength: 4;
maxLength: undefined;
tuplePrefix: readonly [string, Date, number, null];
arrayTail: readonly boolean[];
}
>;
//=> type T4 = true
tsAssertTrue<T4>(); // Compiles without error
tsAssertTrue<T2>(); // Does not compile
type T5 = ReplaceAllTypeOccurrences<
{ foo: string; bar: () => string },
string,
number
>;
//=> type T5 = { foo: number; bar: () => number }
type T6 = IfAny<any, 'hello', 'world'>;
//=> type T6 = 'hello';
type T7 = IfAny<unknown, 'hello', 'world'>;
//=> type T7 = 'world';
type T8 = IfNever<1 & 2, 'hello', 'world'>;
//=> type T8 = 'hello';
type T9 = { a: string; b: string | number };
const someValue =
tsAssertTypeAcceptsValue()<T9>()(
// Autocomplete for `a` and `b` available on the object below
{ a: 'hello', b: 123 } as const
);
tsAssertTypesExactlyEqual()<typeof someValue>()<{ a: 'hello'; b: 123 }>();
tsAssertExtends()<typeof someValue>()<T9>();TODO