type-fest - npm Package Compare versions

Comparing version 0.7.1 to 0.8.0

index.d.ts

@@ -10,2 +10,4 @@ // Basic
 export {RequireAtLeastOne} from './source/require-at-least-one';
+export {RequireExactlyOne} from './source/require-exactly-one';
+export {PartialDeep} from './source/partial-deep';
 export {ReadonlyDeep} from './source/readonly-deep';
@@ -15,4 +17,6 @@ export {LiteralUnion} from './source/literal-union';
 export {Opaque} from './source/opaque';
+export {SetOptional} from './source/set-optional';
+export {SetRequired} from './source/set-required';
 
 // Miscellaneous
 export {PackageJson} from './source/package-json';

package.json

 {
 	"name": "type-fest",
-	"version": "0.7.1",
+	"version": "0.8.0",
 	"description": "A collection of essential TypeScript types",
@@ -35,5 +35,5 @@ "license": "(MIT OR CC0-1.0)",
 		"@sindresorhus/tsconfig": "^0.4.0",
-		"@typescript-eslint/eslint-plugin": "^1.9.0",
-		"@typescript-eslint/parser": "^1.10.2",
-		"eslint-config-xo-typescript": "^0.14.0",
+		"@typescript-eslint/eslint-plugin": "^2.2.0",
+		"@typescript-eslint/parser": "^2.2.0",
+		"eslint-config-xo-typescript": "^0.18.0",
 		"tsd": "^0.7.3",
@@ -40,0 +40,0 @@ "xo": "^0.24.0"

readme.md

@@ -68,10 +68,14 @@ <div align="center">
 - [`Except`](source/except.d.ts) - Create a type from an object type without certain keys. This is a stricter version of [`Omit`](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-5.html#the-omit-helper-type).
-- [`Mutable`](source/mutable.d.ts) - Convert an object with `readonly` properties into a mutable object. Inverse of `Readonly<T>`.
+- [`Mutable`](source/mutable.d.ts) - Convert an object with `readonly` keys into a mutable object. The inverse of `Readonly<T>`.
 - [`Merge`](source/merge.d.ts) - Merge two types into a new type. Keys of the second type overrides keys of the first type.
-- [`MergeExclusive`](source/merge-exclusive.d.ts) - Create a type that has mutually exclusive properties.
-- [`RequireAtLeastOne`](source/require-at-least-one.d.ts) - Create a type that requires at least one of the given properties.
-- [`ReadonlyDeep`](source/readonly-deep.d.ts) - Create a deeply immutable version of a `object`/`Map`/`Set`/`Array` type.
+- [`MergeExclusive`](source/merge-exclusive.d.ts) - Create a type that has mutually exclusive keys.
+- [`RequireAtLeastOne`](source/require-at-least-one.d.ts) - Create a type that requires at least one of the given keys.
+- [`RequireExactlyOne`](source/require-one.d.ts) - Create a type that requires exactly a single key of the given keys and disallows more.
+- [`PartialDeep`](source/partial-deep.d.ts) - Create a deeply optional version of another type. Use [`Partial<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1401-L1406) if you only need one level deep.
+- [`ReadonlyDeep`](source/readonly-deep.d.ts) - Create a deeply immutable version of an `object`/`Map`/`Set`/`Array` type. Use [`Readonly<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1415-L1420) if you only need one level deep.
 - [`LiteralUnion`](source/literal-union.d.ts) - Create a union type by combining primitive types and literal types without sacrificing auto-completion in IDEs for the literal type part of the union. Workaround for [Microsoft/TypeScript#29729](https://github.com/Microsoft/TypeScript/issues/29729).
 - [`Promisable`](source/promisable.d.ts) - Create a type that represents either the value or the value wrapped in `PromiseLike`.
 - [`Opaque`](source/opaque.d.ts) - Create an [opaque type](https://codemix.com/opaque-types-in-javascript/).
+- [`SetOptional`](source/set-optional.d.ts) - Create a type that makes the given keys optional.
+- [`SetRequired`](source/set-required.d.ts) - Create a type that makes the given keys required.
 
@@ -97,14 +101,511 @@ ### Miscellaneous
 - [`Partial<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1401-L1406) - Make all properties in `T` optional.
+	<details>
+	<summary>
+			Example
+	</summary>
+
+	[Playground](https://typescript-play.js.org/?target=6#code/KYOwrgtgBAMg9gcxsAbsANlA3gKClAeQDMiAaPKAEWACMwFz8BRAJxbhcagDEBDAF17ocAXxw4AliH7AWRXgGNgUAHJwAJsADCcEEQkJsFXgAcTK3hGAAuKAGd+LKQgDcFEx363wEGrLf46IjIaOi28EioGG5iOArovHZ2qhrAAIJmAEJgEuiaLEb4Jk4oAsoKuvoIYCwCErq2apo6egZQALyF+FCm5pY2UABETelmg1xFnrYAzAAM8xNQQZGh4cFR6AB0xEQUIm4UFa0IABRHVbYACrws-BJCADwjLVUAfACUXfhEHFBnug4oABrYAATygcCIhBoACtgAp+JsQaC7P9ju9Prhut0joCwCZ1GUAGpCMDKTrnAwAbWRPWSyMhKWalQMAF0Dtj8BIoSd8YSZCT0GSOu1OmAQJp9CBgOpPkc7uBgBzOfwABYSOybSnVWp3XQ0sF04FgxnPFkIVkdKB84mkpUUfCxbEsYD8GogKBqjUBKBiWIAen9UGut3u6CeqReBlePXQQQA7skwMl+HAoMU4CgJJoISB0ODeOmbvwIVC1cAcIGmdpzVApDI5IpgJscNL49WMiZsrl8id3lrzScsD0zBYrLZBgAVOCUOCdwa+95uIA)
+
+	```ts
+	interface NodeConfig {
+			appName: string;
+			port: number;
+	}
+
+	class NodeAppBuilder {
+			private configuration: NodeConfig = {
+					appName: 'NodeApp',
+					port: 3000
+			};
+
+			config(config: Partial<NodeConfig>) {
+					type NodeConfigKey = keyof NodeConfig;
+
+					for (const key of Object.keys(config) as NodeConfigKey[]) {
+							const updateValue = config[key];
+
+							if (updateValue === undefined) {
+									continue;
+							}
+
+							this.configuration[key] = updateValue;
+					}
+
+					return this;
+			}
+	}
+
+	// `Partial<NodeConfig>`` allows us to provide only a part of the
+	// NodeConfig interface.
+	new NodeAppBuilder().config({appName: 'ToDoApp'});
+	```
+	</details>
+
 - [`Required<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1408-L1413) - Make all properties in `T` required.
+	<details>
+	<summary>
+			Example
+	</summary>
+
+	[Playground](https://typescript-play.js.org/?target=6#code/AQ4SwOwFwUwJwGYEMDGNgGED21VQGJZwC2wA3gFCjXAzFJgA2A-AFzADOUckA5gNxUaIYjA4ckvGG07c+g6gF8KQkAgCuEFFDA5O6gEbEwUbLm2ESwABQIixACJIoSdgCUYAR3Vg4MACYAPGYuFvYAfACU5Ko0APRxwADKMBD+wFAAFuh2Vv7OSBlYGdmc8ABu8LHKsRyGxqY4oQT21pTCIHQMjOwA5DAAHgACxAAOjDAAdChYxL0ANLHUouKSMH0AEmAAhJhY6ozpAJ77GTCMjMCiV0ToSAb7UJPPC9WRgrEJwAAqR6MwSRQPFGUFocDgRHYxnEfGAowh-zgUCOwF6KwkUl6tXqJhCeEsxDaS1AXSYfUGI3GUxmc0WSneQA)
+
+	```ts
+	interface ContactForm {
+			email?: string;
+			message?: string;
+	}
+
+	function submitContactForm(formData: Required<ContactForm>) {
+			// Send the form data to the server.
+	}
+
+	submitContactForm({
+			email: '[e-mail]',
+			message: 'Hi! Could you tell me more about…',
+	});
+
+	// TypeScript error: missing property 'message'
+	submitContactForm({
+			email: '[e-mail]',
+	});
+	```
+	</details>
+
 - [`Readonly<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1415-L1420) - Make all properties in `T` readonly.
+	<details>
+	<summary>
+			Example
+	</summary>
+
+	[Playground](https://typescript-play.js.org/?target=6#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)
+
+	```ts
+	enum LogLevel {
+			Off,
+			Debug,
+			Error,
+			Fatal
+	};
+
+	interface LoggerConfig {
+			name: string;
+			level: LogLevel;
+	}
+
+	class Logger {
+			config: Readonly<LoggerConfig>;
+
+			constructor({name, level}: LoggerConfig) {
+					this.config = {name, level};
+					Object.freeze(this.config);
+			}
+	}
+
+	const config: LoggerConfig = {
+		name: 'MyApp',
+		level: LogLevel.Debug
+	};
+
+	const logger = new Logger(config);
+
+	// TypeScript Error: cannot assign to read-only property.
+	logger.config.level = LogLevel.Error;
+
+	// We are able to edit config variable as we please.
+	config.level = LogLevel.Error;
+	```
+	</details>
+
 - [`Pick<T, K>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1422-L1427) - From `T`, pick a set of properties whose keys are in the union `K`.
+	<details>
+	<summary>
+			Example
+	</summary>
+
+	[Playground](https://typescript-play.js.org/?target=6#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)
+
+	```ts
+	interface Article {
+			title: string;
+			thumbnail: string;
+			content: string;
+	}
+
+	// Creates new type out of the `Article` interface composed
+	// from the Articles' two properties: `title` and `thumbnail`.
+	// `ArticlePreview = {title: string; thumbnail: string}`
+	type ArticlePreview = Pick<Article, 'title' | 'thumbnail'>;
+
+	// Render a list of articles using only title and description.
+	function renderArticlePreviews(previews: ArticlePreview[]): HTMLElement {
+			const articles = document.createElement('div');
+
+			for (const preview of previews) {
+					// Append preview to the articles.
+			}
+
+			return articles;
+	}
+
+	const articles = renderArticlePreviews([
+			{
+				title: 'TypeScript tutorial!',
+				thumbnail: '/assets/ts.jpg'
+			}
+	]);
+	```
+	</details>
+
 - [`Record<K, T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1429-L1434) - Construct a type with a set of properties `K` of type `T`.
+	<details>
+	<summary>
+			Example
+	</summary>
+
+	[Playground](https://typescript-play.js.org/?target=6#code/AQ4ejYAUHsGcCWAXBMB2dgwGbAKYC2ADgDYwCeeemCaWArgE7ADGMxAhmuQHQBQoYEnJE8wALKEARnkaxEKdMAC8wAOS0kstGuAAfdQBM8ANzxlRjXQbVaWACwC0JPB0NqA3HwGgIwAJJoWozYHCxixnAsjAhStADmwESMMJYo1Fi4HMCIaPEu+MRklHj8gpqyoeHAAKJFFFTAAN4+giDYCIxwSAByHAR4AFw5SDF5Xm2gJBzdfQPD3WPxE5PAlBxdAPLYNQAelgh4aOHDaPQEMowrIAC+3oJ+AMKMrlrAXFhSAFZ4LEhC9g4-0BmA4JBISXgiCkBQABpILrJ5MhUGhYcATGD6Bk4Hh-jNgABrPDkOBlXyQAAq9ngYmJpOAAHcEOCRjAXqwYODfoo6DhakUSph+Uh7GI4P0xER4Cj0OSQGwMP8tP1hgAlX7swwAHgRl2RvIANALSA08ABtAC6AD4VM1Wm0Kow0MMrYaHYJjGYLLJXZb3at1HYnC43Go-QHQDcvA6-JsmEJXARgCDgMYWAhjIYhDAU+YiMAAFIwex0ZmilMITCGF79TLAGRsAgJYAAZRwSEZGzEABFTOZUrJ5Yn+jwnWgeER6HB7AAKJrADpdXqS4ZqYultTG6azVfqHswPBbtauLY7fayQ7HIbAAAMwBuAEoYw9IBq2Ixs9h2eFMOQYPQObALQKJgggABeYhghCIpikkKRpOQRIknAsZUiIeCttECBEP8NSMCkjDDAARMGziuIYxHwYOjDCMBmDNnAuTxA6irdCOBB1Lh5Dqpqn66tISIykawBnOCtqqC0gbjqc9DgpGkxegOliyfJDrRkAA)
+
+	```ts
+	// Positions of employees in our company.
+	type MemberPosition = 'intern' | 'developer' | 'tech-lead';
+
+	// Interface describing properties of a single employee.
+	interface Employee {
+			firstName: string;
+			lastName: string;
+			yearsOfExperience: number;
+	}
+
+	// Create an object that has all possible `MemberPosition` values set as keys.
+	// Those keys will store a collection of Employees of the same position.
+	const team: Record<MemberPosition, Employee[]> = {
+			intern: [],
+			developer: [],
+			'tech-lead': [],
+	};
+
+	// Our team has decided to help John with his dream of becoming Software Developer.
+	team.intern.push({
+		firstName: 'John',
+		lastName: 'Doe',
+		yearsOfExperience: 0
+	});
+
+	// `Record` forces you to initialize all of the property keys.
+	// TypeScript Error: "tech-lead" property is missing
+	const teamEmpty: Record<MemberPosition, null> = {
+			intern: null,
+			developer: null,
+	};
+	```
+	</details>
+
 - [`Exclude<T, U>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1436-L1439) - Exclude from `T` those types that are assignable to `U`.
+	<details>
+	<summary>
+			Example
+	</summary>
+
+	[Playground](https://typescript-play.js.org/?target=6#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)
+
+	```ts
+	interface ServerConfig {
+		port: null | string | number;
+	}
+
+	type RequestHandler = (request: Request, response: Response) => void;
+
+	// Exclude `null` type from `null | string | number`.
+	// In case the port is equal to `null`, we will use default value.
+	function getPortValue(port: Exclude<ServerConfig['port'], null>): number {
+		if (typeof port === 'string') {
+			return parseInt(port, 10);
+		}
+
+		return port;
+	}
+
+	function startServer(handler: RequestHandler, config: ServerConfig): void {
+		const server = require('http').createServer(handler);
+
+		const port = config.port === null ? 3000 : getPortValue(config.port);
+		server.listen(port);
+	}
+	```
+	</details>
+
 - [`Extract<T, U>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1441-L1444) - Extract from `T` those types that are assignable to `U`.
+	<details>
+	<summary>
+			Example
+	</summary>
+
+	[Playground](https://typescript-play.js.org/?target=6#code/CYUwxgNghgTiAEAzArgOzAFwJYHtXzSwEdkQBJYACgEoAueVZAWwCMQYBuAKDDwGcM8MgBF4AXngBlAJ6scESgHIRi6ty5ZUGdoihgEABXZ888AN5d48ANoiAuvUat23K6ihMQ9ATE0BzV3goPy8GZjZOLgBfLi4Aejj4AEEICBwAdz54MAALKFQQ+BxEeAAHY1NgKAwoIKy0grr4DByEUpgccpgMaXgAaxBerCzi+B9-ZulygDouFHRsU1z8kKMYE1RhaqgAHkt4AHkWACt4EAAPbVRgLLWNgBp9gGlBs8uQa6yAUUuYPQwdgNpKM7nh7mMML4CgA+R5WABqUAgpDeVxuhxO1he0jsXGh8EoOBO9COx3BQPo2PBADckaR6IjkSA6PBqTgsMBzPsicdrEC7OJWXSQNwYvFEgAVTS9JLXODpeDpKBZFg4GCoWa8VACIJykAKiQWKy2YQOAioYikCg0OEMDyhRSy4DyxS24KhAAMjyi6gS8AAwjh5OD0iBFHAkJoEOksC1mnkMJq8gUQKDNttKPlnfrwYp3J5XfBHXqoKpfYkAOI4ansTxaeDADmoRSCCBYAbxhC6TDx6rwYHIRX5bScjA4bLJwoDmDwDkfbA9JMrVMVdM1TN69LgkTgwgkchUahqIA)
+
+	```ts
+	declare function uniqueId(): number;
+
+	const ID = Symbol('ID');
+
+	interface Person {
+		[ID]: number;
+		name: string;
+		age: number;
+	}
+
+	// Allows changing the person data as long as the property key is of string type.
+	function changePersonData<
+		Obj extends Person,
+		Key extends Extract<keyof Person, string>,
+		Value extends Obj[Key]
+	> (obj: Obj, key: Key, value: Value): void {
+		obj[key] = value;
+	}
+
+	// Tiny Andrew was born.
+	const andrew = {
+		[ID]: uniqueId(),
+		name: 'Andrew',
+		age: 0,
+	};
+
+	// Cool, we're fine with that.
+	changePersonData(andrew, 'name', 'Pony');
+
+	// Goverment didn't like the fact that you wanted to change your identity.
+	changePersonData(andrew, ID, uniqueId());
+	```
+	</details>
+
 - [`NonNullable<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1446-L1449) - Exclude `null` and `undefined` from `T`.
+	<details>
+	<summary>
+			Example
+	</summary>
+	Works with <code>strictNullChecks</code> set to <code>true</code>. (Read more <a href="https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-0.html">here</a>)
+
+	[Playground](https://typescript-play.js.org/?target=6#code/C4TwDgpgBACg9gJ2AOQK4FsBGEFQLxQDOwCAlgHYDmUAPlORtrnQwDasDcAUFwPQBU-WAEMkUOADMowqAGNWwwoSgATCBIqlgpOOSjAAFsOBRSy1IQgr9cKJlSlW1mZYQA3HFH68u8xcoBlHA8EACEHJ08Aby4oKDBUTFZSWXjEFEYcAEIALihkXTR2YSSIAB54JDQsHAA+blj4xOTUsHSACkMzPKD3HHDHNQQAGjSkPMqMmoQASh7g-oihqBi4uNIpdraxPAI2VhmVxrX9AzMAOm2ppnwoAA4ABifuE4BfKAhWSyOTuK7CS7pao3AhXF5rV48E4ICDAVAIPT-cGQyG+XTEIgLMJLTx7CAAdygvRCA0iCHaMwarhJOIQjUBSHaACJHk8mYdeLwxtdcVAAOSsh58+lXdr7Dlcq7A3n3J4PEUdADMcspUE53OluAIUGVTx46oAKuAIAFZGQwCYAKIIBCILjUxaDHAMnla+iodjcIA)
+
+	```ts
+	type PortNumber = string | number | null;
+
+	/** Part of a class definition that is used to build a server */
+	class ServerBuilder {
+			portNumber!: NonNullable<PortNumber>;
+
+			port(this: ServerBuilder, port: PortNumber): ServerBuilder {
+					if (port == null) {
+							this.portNumber = 8000;
+					} else {
+							this.portNumber = port;
+					}
+
+					return this;
+			}
+	}
+
+	const serverBuilder = new ServerBuilder();
+
+	serverBuilder
+			.port('8000')   // portNumber = '8000'
+			.port(null)     // portNumber =  8000
+			.port(3000);    // portNumber =  3000
+
+	// TypeScript error
+	serverBuilder.portNumber = null;
+	```
+	</details>
+
 - [`Parameters<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1451-L1454) - Obtain the parameters of a function type in a tuple.
+	<details>
+	<summary>
+			Example
+	</summary>
+
+	[Playground](https://typescript-play.js.org/?target=6#code/GYVwdgxgLglg9mABAZwBYmMANgUwBQxgAOIUAXIgIZgCeA2gLoCUFAbnDACaIDeAUIkQB6IYgCypSlBxUATrMo1ECsJzgBbLEoipqAc0J7EMKMgDkiHLnU4wp46pwAPHMgB0fAL58+oSLARECEosLAA5ABUYG2QAHgAxJGdpVWREPDdMylk9ZApqemZEAF4APipacrw-CApEgBogkKwAYThwckQwEHUAIxxZJl4BYVEImiIZKF0oZRwiWVdbeygJmThgOYgcGFYcbhqApCJsyhtpWXcR1cnEePBoeDAABVPzgbTixFeFd8uEsClADcIxGiygIFkSEOT3SmTc2VydQeRx+ZxwF2QQ34gkEwDgsnSuFmMBKiAADEDjIhYk1Qm0OlSYABqZnYka4xA1DJZHJYkGc7yCbyeRA+CAIZCzNAYbA4CIAdxg2zJwVCkWirjwMswuEaACYmCCgA)
+
+	```ts
+	function shuffle(input: any[]): void {
+		// Mutate array randomly changing its' elements indexes.
+	}
+
+	function callNTimes<Fn extends (...args: any[]) => any> (func: Fn, callCount: number) {
+		// Type that represents the type of the received function parameters.
+		type FunctionParameters = Parameters<Fn>;
+
+		return function (...args: FunctionParameters) {
+			for (let i = 0; i < callCount; i++) {
+				func(...args);
+			}
+		}
+	}
+
+	const shuffleTwice = callNTimes(shuffle, 2);
+	```
+	</details>
+
 - [`ConstructorParameters<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1456-L1459) - Obtain the parameters of a constructor function type in a tuple.
+	<details>
+	<summary>
+			Example
+	</summary>
+
+	[Playground](https://typescript-play.js.org/?target=6#code/MYGwhgzhAECCBOAXAlqApgWQPYBM0mgG8AoaaFRENALmgkXmQDsBzAblOmCycTV4D8teo1YdO3JiICuwRFngAKClWENmLAJRFOZRAAtkEAHQq00ALzlklNBzIBfYk+KhIMAJJTEYJsDQAwmDA+mgAPAAq0GgAHnxMODCKTGgA7tCKxllg8CwQtL4AngDaALraFgB80EWa1SRkAA6MAG5gfNAB4FABPDJyCrQR9tDNyG0dwMGhtBhgjWEiGgA00F70vv4RhY3hEZXVVinpc42KmuJkkv3y8Bly8EPaDWTkhiZd7r3e8LK3llwGCMXGQWGhEOsfH5zJlsrl8p0+gw-goAAo5MAAW3BaHgEEilU0tEhmzQ212BJ0ry4SOg+kg+gBBiMximIGA0nAfAQLGk2N4EAAEgzYcYcnkLsRdDTvNEYkYUKwSdCme9WdM0MYwYhFPSIPpJdTkAAzDKxBUaZX+aAAQgsVmkCTQxuYaBw2ng4Ok8CYcotSu8pMur09iG9vuObxZnx6SN+AyUWTF8MN0CcZE4Ywm5jZHK5aB5fP4iCFIqT4oRRTKRLo6lYVNeAHpG50wOzOe1zHr9NLQ+HoABybsD4HOKXXRA1JCoKhBELmI5pNaB6Fz0KKBAodDYPAgSUTmqYsAALx4m5nC6nW9nGq14KtaEUA9gR9PvuNCjQ9BgACNvcwNBtAcLiAA)
+
+	```ts
+	class ArticleModel {
+		title: string;
+		content?: string;
+
+		constructor(title: string) {
+			this.title = title;
+		}
+	}
+
+	class InstanceCache<T extends (new (...args: any[]) => any)> {
+		private ClassConstructor: T;
+		private cache: Map<string, InstanceType<T>> = new Map();
+
+		constructor (ctr: T) {
+			this.ClassConstructor = ctr;
+		}
+
+		getInstance (...args: ConstructorParameters<T>): InstanceType<T> {
+			const hash = this.calculateArgumentsHash(...args);
+
+			const existingInstance = this.cache.get(hash);
+			if (existingInstance !== undefined) {
+				return existingInstance;
+			}
+
+			return new this.ClassConstructor(...args);
+		}
+
+		private calculateArgumentsHash(...args: any[]): string {
+			// Calculate hash.
+			return 'hash';
+		}
+	}
+
+	const articleCache = new InstanceCache(ArticleModel);
+	const amazonArticle = articleCache.getInstance('Amazon forests burining!');
+	```
+	</details>
+
 - [`ReturnType<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1461-L1464) – Obtain the return type of a function type.
+	<details>
+	<summary>
+			Example
+	</summary>
+
+	[Playground](https://typescript-play.js.org/?target=6#code/MYGwhgzhAECSAmICmBlJAnAbgS2E6A3gFDTTwD2AcuQC4AW2AdgOYAUAlAFzSbnbyEAvkWFFQkGJSQB3GMVI1sNZNwg10TZgG4S0YOUY0kh1es07d+xmvQBXYDXLpWi5UlMaWAGj0GjJ6BtNdkJdBQYIADpXZGgAXmgYpB1ScOwoq38aeN9DYxoU6GFRKzVoJjUwRjwAYXJbPPRuAFkwAAcAHgAxBodsAx9GWwBbACMMAD4cxhloVraOCyYjdAAzMDxoOut1e0d0UNIZ6WhWSPOwdGYIbiqATwBtAF0uaHudUQB6ACpv6ABpJBINqJdAbADW0Do5BOw3u5R2VTwMHIq2gAANtjZ0bkbHsnFCwJh8ONjHp0EgwEZ4JFoN9PkRVr1FAZoMwkDRYIjqkgOrosepoEgAB7+eAwAV2BxOLy6ACCVxgIrFEoMeOl6AACpcwMMORgIB1JRMiBNWKVdhruJKfOdIpdrtwFddXlzKjyACp3Nq842HaDIbL6BrZBIVGhIpB1EMYSLsmjmtWW-YhAA+qegAAYLKQLQj3ZsEsdccmnGcLor2Dn8xGedHGpEIBzEzspfsfMHDNAANTQACMVaIljV5GQkRA5DYmIpVKQAgAJARO9le33BDXIyi0YuLW2nJFGLqkOvxFB0YPdBSaLZ0IwNzyPkO8-xkGgsLh8Al427a3hWAhXwwHA8EHT5PmgAB1bAQBAANJ24adKWpft72RaBUTgRBUCAj89HAM8xCTaBjggABRQx0DuHJv25P9dCkWRZVIAAiBjoFImpmjlFBgA0NpsjadByDacgIDAEAIAAQmYpjoGYgAZSBsmGPw6DtZiiFA8CoJguDmAQmoZ2QvtUKQLdoAYmBTwgdEiCAA)
+
+	```ts
+	/** Provides every element of the iterable `iter` into the `callback` function and stores the results in an array. */
+	function mapIter<
+			Elem,
+			Func extends (elem: Elem) => any,
+			Ret extends ReturnType<Func>
+	>(iter: Iterable<Elem>, callback: Func): Ret[] {
+			const mapped: Ret[] = [];
+
+			for (const elem of iter) {
+					mapped.push(callback(elem));
+			}
+
+			return mapped;
+	}
+
+	const setObject: Set<string> = new Set();
+	const mapObject: Map<number, string> = new Map();
+
+	mapIter(setObject, (value: string) => value.indexOf('Foo')); // number[]
+
+	mapIter(mapObject, ([key, value]: [number, string]) => {
+			return key % 2 === 0 ? value : 'Odd';
+	}); // string[]
+	```
+	</details>
+
 - [`InstanceType<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1466-L1469) – Obtain the instance type of a constructor function type.
+	<details>
+	<summary>
+			Example
+	</summary>
 
+	[Playground](https://typescript-play.js.org/?target=6#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-YhAA+qegAAYLKQLQj3ZsEsdccmnGcLor2Dn8xGedHGpEIBzEzspfsfMHDNAANTQACMVaIljV5GQkRA5DYmIpVKQAgAJARO9le33BDXIyi0YuLW2nJFGLqkOvxFB0YPdBSaLZ0IwNzyPkO8-xkGgsLh8Al427a3hWAhXwwHA8EHT5PmgAB1bAQBAANJ24adKWpft72RaBUTgRBUCAj89HAM8xCTaBjggABRQx0DuHJv25P9dCkWRZVIAAiBjoFImpmjlFBgA0NpsjadByDacgIDAEAIAAQmYpjoGYgAZSBsmGPw6DtZiiFA8CoJguDmAQmoZ2QvtUKQLdoAYmBTwgdEiCAA)
+
+	```ts
+	class IdleService {
+			doNothing (): void {}
+	}
+
+	class News {
+			title: string;
+			content: string;
+
+			constructor(title: string, content: string) {
+					this.title = title;
+					this.content = content;
+			}
+	}
+
+	const instanceCounter: Map<Function, number> = new Map();
+
+	interface Constructor {
+			new(...args: any[]): any;
+	}
+
+	// Keep track how many instances of `Constr` constructor have been created.
+	function getInstance<
+			Constr extends Constructor,
+			Args extends ConstructorParameters<Constr>
+	>(constructor: Constr, ...args: Args): InstanceType<Constr> {
+			let count = instanceCounter.get(constructor) || 0;
+
+			const instance = new constructor(...args);
+
+			instanceCounter.set(constructor, count + 1);
+
+			console.log(`Created ${count + 1} instances of ${Constr.name} class`);
+
+			return instance;
+	}
+
+
+	const idleService = getInstance(IdleService);
+	// Will log: `Created 1 instances of IdleService class`
+	const newsEntry = getInstance(News, 'New ECMAScript proposals!', 'Last month...');
+	// Will log: `Created 1 instances of News class`
+	```
+	</details>
+
+- [`Omit<T, K>`](https://github.com/microsoft/TypeScript/blob/71af02f7459dc812e85ac31365bfe23daf14b4e4/src/lib/es5.d.ts#L1446) – Constructs a type by picking all properties from T and then removing K.
+	<details>
+	<summary>
+			Example
+	</summary>
+
+	[Playground](https://typescript-play.js.org/?target=6#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-SgfXlHqVUE4xiAA)
+
+	```ts
+	interface Animal {
+			imageUrl: string;
+			species: string;
+			images: string[];
+			paragraphs: string[];
+	}
+
+	// Creates new type with all properties of the `Animal` interface
+	// except 'images' and 'paragraphs' properties. We can use this
+	// type to render small hover tooltip for a wiki entry list.
+	type AnimalShortInfo = Omit<Animal, 'images' | 'paragraphs'>;
+
+	function renderAnimalHoverInfo (animals: AnimalShortInfo[]): HTMLElement {
+			const container =  document.createElement('div');
+			// Internal implementation.
+			return container;
+	}
+	```
+	</details>
+
 You can find some examples in the [TypeScript docs](https://www.typescriptlang.org/docs/handbook/advanced-types.html#predefined-conditional-types).
@@ -123,1 +624,14 @@
 (MIT OR CC0-1.0)
+
+
+---
+
+<div align="center">
+	<b>
+		<a href="https://tidelift.com/subscription/pkg/npm-type-fest?utm_source=npm-type-fest&utm_medium=referral&utm_campaign=readme">Get professional support for this package with a Tidelift subscription</a>
+	</b>
+	<br>
+	<sub>
+		Tidelift helps make open source sustainable for maintainers while giving companies<br>assurances about security, maintenance, and licensing for their dependencies.
+	</sub>
+</div>

source/merge-exclusive.d.ts

@@ -5,3 +5,3 @@ // Helper type. Not useful on its own.
 /**
-Create a type that has mutually exclusive properties.
+Create a type that has mutually exclusive keys.
 
@@ -8,0 +8,0 @@ This type was inspired by [this comment](https://github.com/Microsoft/TypeScript/issues/14094#issuecomment-373782604).

source/mutable.d.ts

 /**
-Convert an object with `readonly` properties into a mutable object. Inverse of `Readonly<T>`.
+Convert an object with `readonly` keys into a mutable object. Inverse of `Readonly<T>`.
 
@@ -20,4 +20,4 @@ This can be used to [store and mutate options within a class](https://github.com/sindresorhus/pageres/blob/4a5d05fca19a5fbd2f53842cbf3eb7b1b63bddd2/source/index.ts#L72), [edit `readonly` objects within tests](https://stackoverflow.com/questions/50703834), and [construct a `readonly` object within a function](https://github.com/Microsoft/TypeScript/issues/24509).
 export type Mutable<ObjectType> = {
-	// For each `Key` in the keys of `ObjectType`, make a mapped type by removing the `readonly` modifier from the property.
+	// For each `Key` in the keys of `ObjectType`, make a mapped type by removing the `readonly` modifier from the key.
 	-readonly [KeyType in keyof ObjectType]: ObjectType[KeyType];
 };

source/readonly-deep.d.ts

 import {Primitive} from './basic';
 
 /**
-Convert `object`s, `Map`s, `Set`s, and `Array`s and all of their properties/elements into immutable structures recursively.
+Convert `object`s, `Map`s, `Set`s, and `Array`s and all of their keys/elements into immutable structures recursively.
 
@@ -58,3 +58,3 @@ This is useful when a deeply nested structure needs to be exposed as completely immutable, for example, an imported JSON module or when receiving an API response that is passed around.
 type ReadonlyObjectDeep<ObjectType extends object> = {
-	readonly [PropertyType in keyof ObjectType]: ReadonlyDeep<ObjectType[PropertyType]>
+	readonly [KeyType in keyof ObjectType]: ReadonlyDeep<ObjectType[KeyType]>
 };

source/require-at-least-one.d.ts

 import {Except} from './except';
 
 /**
-Create a type that requires at least one of the given properties. The remaining properties are kept as is.
+Create a type that requires at least one of the given keys. The remaining keys are kept as is.
 
@@ -31,3 +31,3 @@ @example
 	}[KeysType]
-	// …then, make intersection types by adding the remaining properties to each mapped type.
+	// …then, make intersection types by adding the remaining keys to each mapped type.
 	& Except<ObjectType, KeysType>;

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Improved metrics

Total package byte prevSize

57548

increased by84.51%

Number of package files

19

increased by26.67%

Lines of code

871

increased by20.8%

Number of lines in readme file

635

increased by424.79%

No dependency changes