@juln/type-fest
v1.5.0
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A collection of essential TypeScript types
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A collection of TypeScript types that have undergone type testing
Based on type-fest
Conduct secondary development and expose all types provided by type-fest
(please refer to the official documentation for the use of type test
, which is not provided here)
Programming Guide for Writing Types:
- The most important aspect of type programming is to clearly know the most basic operations, which are joint to joint, joint to cross, cross to cross, and irreversible.
- Then the rest is logical splitting, breaking it down into various types of functions, and assembling them together, and that's all.
common-types
Negate
true -> false; false -> true
type False = Negate<true>; // false
type True = Negate<false>; // true
IsVoid
(void extends T) and (T extends void)
IsUndefined
(undefined extends T) and (T extends undefined)
IsObject
(object extends T) and (T extends object)
IsValue
filter out never
and void
function-types (about function)
PromiseFn
Change the return value of a function that is not promise
to promise
type OriginalFn = (a: 1, b: 2) => number;
type Fn = PromiseFn<OriginalFn>; // (a: 1, b: 2) => Promise<number>
PromisableFn
Change the return value of a function that is not promise
to promisable
type OriginalFn = (a: 1, b: 2) => number;
type Fn = PromisableFn<OriginalFn>; // (a: 1, b: 2) => Promise<number> | number
array-types (about array)
ReadonlyArray
type OriginalArr = [1, ''];
type Arr = ReadonlyArray<OriginalArr>; // readonly [1, '']
PureArray
filter out never
and void
type OriginalArr = [1, '', false, number, string, boolean, symbol, {}, object, Error, null, undefined, never, void];
type Arr = PureArray<OriginalArr>; // [1, "", false, number, string, boolean, symbol, {}, object, Error, null, undefined]
type ReadonlyOriginalArr = readonly [1, 2, never, void];
type ReadonlyArr = PureArray<ReadonlyOriginalArr>; // readonly [1, 2]
object-types (about object)
Spreadable
type Obj = {
a: 1;
b: 2;
c: 3;
};
type ObjIsSpreadable = Obj extends Spreadable ? true : false; // true
DeepKeysOfSpreadable
Get all keys of an spreadable type recursively.
type Obj = {
0: string;
a: {
b: {
c: string;
d: string;
};
};
e: string;
f: string;
[Symbol.hasInstance]: 0;
};
type Keys = DeepKeysOfSpreadable<Obj>; // `Keys` equivalent to 0 | 'c' | 'd' | 'f' | Symbol.hasInstance;
MergeObjects
Merge multiple objects
type O1 = {
a: 'a';
c: 'c';
d: {
d1: 0;
};
e: 'e';
f: 'f1';
};
type O2 = {
b: 'b';
c: 'c';
d: {
d2: 1;
};
e: { e: 'e'; };
f: 'f2';
};
type Res = MergeObjects<[O1, O2, ...]>; // { a?: 'a'; b?: 'b'; c: 'c'; d: { d1?: 0; d2?: 1; }; e: 'e' | { e: 'e'; }; f: 'f1' | 'f2'; };
MixedTuple
Merge multiple objects. like MergeObjects
type Res = MergeObjects<O1 | O2>;
TuplifyUnion
Union to tuple, but You can't rely on the ordering of a union type. It's an implementation detail of the compiler; since X | Y is equivalent to Y | X, the compiler feels free to change one to the other.
type abc = 'a' | 'b' | 'c';
type t = TuplifyUnion<abc>; // ["a", "b", "c"]
color-types (about color)
HexColor
verify hexadecimal color values
type Res1 = HexColor<'#fff'> // '#fff';
type Res2 = HexColor<'#ffffff'> // '#ffffff';
type Res3 = HexColor<'#xxx'> // never;
better-typed
Strengthening the TS type for third-party libraries
TypedRPC
Strengthen @mixer/postmessage-rpc
import { RPC } from "@mixer/postmessage-rpc";
import type { TypedRPC } from "@juln/type-fest";
/**
* Only 'type' can be used, not 'interface', otherwise lax type constraints will cause problems
*
* type ExposeMap = {
* "exposeName1": {
* isPromise: true;
* params: any;
* data: any;
* };
* "exposeName2": {
* isPromise: true;
* params: any;
* data: any;
* };
* ...
* }
*/
type ExposeMap = {
'load-error': {
data: Error;
};
'close-window': {};
'result': {
isPromise: true;
params: {
pageNum?: number;
pageSize?: number;
};
data: {
code: number;
list: any[];
};
};
}
type CallMap = {
'simpleLoad': {};
'load': {
params: {
immediately?: boolean;
};
data: {
success: boolean;
};
};
'close-modal': {};
}
const rpc: TypedRPC<ExposeMap, CallMap> = new RPC({
target: window.top!,
serviceId: "test",
});
rpc.call("close-modal", {}); // Restrictions on types such as 'eventName', 'params', and 'returnType'
rpc.call("unknown", {}); // 'eventName' not declared, type error reported
// 2. In non strict mode, for undeclared 'eventName', the type does not report an error, and the 'handler' is: (params: any) => Promise<any> | any)
(rpc as TypedRPC<ExposeMap, CallMap, false>).expose('unkown', a => a);
TypedEventEmitter
Strengthen eventemitter3
import { EventEmitter } from "eventEmitter3";
import type { TypedEventEmitter } from "@juln/type-fest";
/**
* interface MyEventMap {
* "eventName1": {
* args: [arg1: any, arg2: any, ...];
* };
* "eventName2": {
* args: [arg1: any, arg2: any, ...];
* };
* ...
* }
*/
interface MyEventMap {
'load-error': {
args: [Error];
};
'close': {
};
'result': {
args: [
result1: number,
result2: string,
result3: null,
];
};
}
const ee = new EventEmitter();
ee.emit('close');