# clone-class > Clone an ES6 Class as Another Class Name for Isolating Class Static Properties. Latest version **1.0.3** (published 2021-11-14) · Apache-2.0 license · 0 weekly downloads ## Install ```sh npm install clone-class pnpm add clone-class yarn add clone-class bun add clone-class ``` ## Health **Score 30/100 (F)** — status: abandoned. Positive: has types; esm support; no vulnerabilities; high quality score. Warnings: low downloads. Negative: abandoned; low maintenance score. ## Facts | | | |---|---| | Version | 1.0.3 | | Published | 2021-11-14 | | First published | 2018-04-23 | | Weekly downloads | 0 | | License | Apache-2.0 | | TypeScript types | bundled | | Module format | ESM | | Node | >=16 | | Dependencies | 0 | | Unpacked size | 142.3 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 4 | | Author | Huan LI | | Maintainers | zixia, chatie | | Keywords | clone, class, es6, static | ## Links - npm: https://www.npmjs.com/package/clone-class - Repository: https://github.com/huan/clone-class - Homepage: https://github.com/huan/clone-class#readme - Issues: https://github.com/huan/clone-class/issues - npm.io page: https://npm.io/package/clone-class ## Recent versions - 1.0.3 (latest) — 2021-11-14 - 1.1.2 (next) — 2022-05-14 - 1.1.3 — 2022-05-14 - 1.1.1 — 2021-11-22 - 1.0.2 — 2021-10-23 - 1.0.1 — 2021-10-23 - 0.10.8 — 2021-10-23 - 0.10.7 — 2021-10-23 - 0.10.6 — 2021-10-20 - 0.10.5 — 2021-10-20 - 0.10.4 — 2021-10-20 - 0.10.3 — 2021-10-20 - 0.10.2 — 2021-10-20 - 0.9.19 — 2021-10-13 - 0.9.18 — 2021-10-05 - … 39 more at https://npm.io/package/clone-class/versions ## README # CLONE CLASS [![NPM Version](https://badge.fury.io/js/clone-class.svg)](https://badge.fury.io/js/clone-class) [![Build Status](https://api.travis-ci.com/huan/clone-class.svg?branch=master)](https://travis-ci.com/huan/clone-class) [![TypeScript](https://img.shields.io/badge/%3C%2F%3E-TypeScript-blue.svg)](https://www.typescriptlang.org/) [![ES Modules](https://img.shields.io/badge/ES-Modules-brightgreen)](https://github.com/Chatie/tsconfig/issues/16) ![Clone Class](https://huan.github.io/clone-class/images/clone-class-logo.png) Clone an ES6 Class as Another Class Name for Isolating Class Static Properties. ## EXAMPLE Run the following example by: ```shell git clone git@github.com:zixia/clone-class.git cd clone-class npm install npm run example ``` ### TypeScript **[Example Source Code](https://github.com/huan/clone-class/blob/master/examples/example.ts):** ```ts import * as assert from 'assert' import { cloneClass, instanceToClass, } from '../src/clone-class' class Employee { public static company: string constructor( public name: string, ) { } public info() { console.log(`Employee ${this.name}, Company ${(this.constructor as any).company}`) } } /** * Example 1: `cloneClass()` */ const GoogleEmployee = cloneClass(Employee) GoogleEmployee.company = 'Google' const MicrosoftEmployee = cloneClass(Employee) MicrosoftEmployee.company = 'Microsoft' const employeeGg = new GoogleEmployee('Tom') const employeeMs = new MicrosoftEmployee('Jerry') employeeGg.info() // Output: Employee Tom, Company Google employeeMs.info() // Output: Employee Jerry, Company Microsoft /** * Example 2: `instanceToClass()` */ const RestoreGoogleEmployee = instanceToClass(employeeGg, Employee) assert(RestoreGoogleEmployee === GoogleEmployee, 'Should get back the Class which instanciated the instance) assert(RestoreGoogleEmployee !== Employee, 'Should be different with the parent Class') const anotherEmployee = new RestoreGoogleEmployee('Mary') anotherEmployee.info() // Output: Employee Mary, Company Google ``` The most tricky part of this code is `(this.constructor as any).company`. It will be very clear after we break down it as the following steps: 1. `this.constructor` is the constructor function of the class, which shuold be the _class function_ itself. 1. `company` is a static properity defined in `Employee` class, which will be set as a property on the _class function_. 1. So `this.constructor.company` is equal to `Employee.company`, except that we will not need to know the exact name of the class, `Employee` in this case. We use this pattern is because we need to visit the _class function_ even we do not know it's name. ## API We have two APIs for dealing with the classes: 1. `cloneClass(OriginalClass)`: create a new Class that is `extend` from the `OriginalClass` which can isolate static properties for stored values, and return the new Class. 1. `instanceToClass(instance, BaseClass)`: get the Class which had instanciated the `instance`, which is the `BaseClass`, or the child class of `BaseClass`, and return it. ### 1. `cloneClass()` ```ts const GoogleEmployee = cloneClass(Employee) const instance = new GoogleEmployee() assert(instance instanceof GoogleEmployee) assert(instance instanceof Employee) assert(GoogleEmployee.name === Employee.name, 'Should be the same class name') ``` ### 2. `instanceToClass()` ```ts const instance = new GoogleEmployee() const RestoredClass = instanceToClass(instance, Employee) assert(RestoredClass === GoogleEmployee, 'because `instance` was created by `new GoogleEmployee()`') ``` ### 3. `Constructor` ```ts class PrivateConstructorClass { private constructor() { console.info('private constructor called') } } const NewableClass = PrivateConstructorClass as any as Constructor const instance = new NewableClass() // Output: private constructor called ``` It seems useless at first, but if you want to use manage many Child Class for a Abstract Class with typings, then it will be a must have tool. ### 4. `looseInstanceOfClass(Klass)(target)` use it to check whether a class instance is: 1. `instanceof` the class `Klass` 1. `instanceof` the class `Klass`'s child class 1. the `constructor.name` is the same as the class `Klass` Usage: ```ts looseInstanceOfClass = (Klass: C) => (target: any): target is InstanceType ``` ### 5. `interfaceOfClass(Klass)()(target)` use it to check where a target object has all the same properties from class `Klass` Usage: ```ts interfaceOfClass = (Klass: C) => () => (target: any): target is I ``` ## CHANGELOG ### master v1.0 (Oct 20, 2021) 1. Add `interfaceOfClass()` method to check whether a object satisfy a class interface. #### v0.9 (Aug 26, 2021) 1. ESM Support 2. GitHub Action enabled 3. add `looseInstanceOfClass()` method to check whether two class has the same name (See ([wechaty/wechaty#2090](https://github.com/wechaty/wechaty/issues/2090))) ### v0.6 (May 2018) 1. add new function: `instanceToClass()` for getting back the `Class` from an existing `instance`. 1. add new type: `Constructor` for adding `new (): T` to abstract class declaration. ### v0.4 (Apr 2018) First publish version. 1. `cloneClass()` work as expected. ### v0.0.1 (Apr 23, 2018) Initial version, code comes from Project Wechaty. Learn more about the full story at Chatie blog: [New Feature: Multi-Instance Support for Wechaty v0.16(WIP)](https://blog.chatie.io/blessed-twins-bot/) ## SEE ALSO An UseCase of `clone-class` can be found in an article writen by me from Chatie blog, it's also the place where this module comes from. It's Worth to spent some time to have a look if you are interested. * [New Feature: Multi-Instance Support for Wechaty v0.16(WIP)](https://blog.chatie.io/blessed-twins-bot/) * [TypeScript 2.1 keyof and Lookup Types](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-1.html) * [TypeScript Evolution](https://blog.mariusschulz.com/series/typescript-evolution) * [TypeScript Advanced Types](https://www.typescriptlang.org/docs/handbook/advanced-types.html) ## AUTHOR [Huan LI](http://linkedin.com/in/zixia) \ profile for zixia on Stack Exchange, a network of free, community-driven Q&A sites ## COPYRIGHT & LICENSE * Code & Docs © 2018 Huan LI \ * Code released under the Apache-2.0 License * Docs released under Creative Commons --- _Source: https://npm.io/package/clone-class · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._