自从TypeScript 3.7发布以来，现在支持递归类型别名，它允许我们定义一个类型安全的deepCopy()函数:

// DeepCopy type can be easily extended by other types,
// like Set & Map if the implementation supports them.
type DeepCopy<T> =
    T extends undefined | null | boolean | string | number ? T :
    T extends Function | Set<any> | Map<any, any> ? unknown :
    T extends ReadonlyArray<infer U> ? Array<DeepCopy<U>> :
    { [K in keyof T]: DeepCopy<T[K]> };

function deepCopy<T>(obj: T): DeepCopy<T> {
    // implementation doesn't matter, just use the simplest
    return JSON.parse(JSON.stringify(obj));
}

interface User {
    name: string,
    achievements: readonly string[],
    extras?: {
        city: string;
    }
}

type UncopiableUser = User & {
    delete: () => void
};

declare const user: User;
const userCopy: User = deepCopy(user); // no errors

declare const uncopiableUser: UncopiableUser;
const uncopiableUserCopy: UncopiableUser = deepCopy(uncopiableUser); // compile time error

操场上

我尝试创建一个通用的复制/克隆服务，为嵌套对象保留类型。会爱反馈，如果我做错了什么，但它似乎工作到目前为止…

import { Injectable } from '@angular/core';

@Injectable()
export class CopyService {

  public deepCopy<T>(objectToClone: T): T {
    // If it's a simple type or null, just return it.
    if (typeof objectToClone === 'string' ||
      typeof objectToClone === 'number' ||
      typeof objectToClone === 'undefined' ||
      typeof objectToClone === 'symbol' ||
      typeof objectToClone === 'function' ||
      typeof objectToClone === 'boolean' ||
      objectToClone === null
    ) {
      return objectToClone;
    }

    // Otherwise, check if it has a constructor we can use to properly instantiate it...
    let ctor = Object.getPrototypeOf(objectToClone).constructor;
    if (ctor) {
      let clone = new ctor();

      // Once we've instantiated the correct type, assign the child properties with deep copies of the values
      Object.keys(objectToClone).forEach(key => {
        if (Array.isArray(objectToClone[key]))
          clone[key] = objectToClone[key].map(item => this.deepCopy(item));
        else
          clone[key] = this.deepCopy(objectToClone[key]);
      });

      if (JSON.stringify(objectToClone) !== JSON.stringify(clone))
        console.warn('object cloned, but doesnt match exactly...\nobject: ' + JSON.stringify(objectToClone) + "\nclone: " + JSON.stringify(clone))

      // return our cloned object...
      return clone;
    }
    else {
      //not sure this will ever get hit, but figured I'd have a catch call.
      console.log('deep copy found something it didnt know: ' + JSON.stringify(objectToClone));
      return objectToClone;
    }
  }
}

这是我的混搭!这里有一个StackBlitz的链接。它目前仅限于复制简单的类型和对象类型，但我认为可以很容易地修改。

   let deepClone = <T>(source: T): { [k: string]: any } => {
      let results: { [k: string]: any } = {};
      for (let P in source) {
        if (typeof source[P] === 'object') {
          results[P] = deepClone(source[P]);
        } else {
          results[P] = source[P];
        }
      }
      return results;
    };

对于可序列化的深度克隆，类型信息为，

export function clone<T>(a: T): T {
  return JSON.parse(JSON.stringify(a));
}

你可以在扩展语法中使用解构赋值:

var obj = {id = 1, name = 'product1'};
var clonedObject = {...obj};

解决具体问题

你可以使用类型断言来告诉编译器你知道的更好:

public clone(): any {
    var cloneObj = new (this.constructor() as any);
    for (var attribut in this) {
        if (typeof this[attribut] === "object") {
            cloneObj[attribut] = this[attribut].clone();
        } else {
            cloneObj[attribut] = this[attribut];
        }
    }
    return cloneObj;
}

克隆

截至2022年，有一项提案允许structuredClone深度复制许多类型。

const copy = structuredClone(value)

对于你可以在什么事情上使用它有一些限制。

请记住，有时候编写自己的映射比完全动态的映射更好。然而，你可以使用一些“克隆”技巧来获得不同的效果。

我将使用以下代码的所有后续示例:

class Example {
  constructor(public type: string) {

  }
}

class Customer {
  constructor(public name: string, public example: Example) {

  }

  greet() {
    return 'Hello ' + this.name;
  }
}

var customer = new Customer('David', new Example('DavidType'));

选择1:分散

属性:是的 方法:没有 深度复制:否

var clone = { ...customer };

alert(clone.name + ' ' + clone.example.type); // David DavidType
//alert(clone.greet()); // Not OK

clone.name = 'Steve';
clone.example.type = 'SteveType';

alert(customer.name + ' ' + customer.example.type); // David SteveType

选项2:Object.assign

属性:是的 方法:没有 深度复制:否

var clone = Object.assign({}, customer);

alert(clone.name + ' ' + clone.example.type); // David DavidType
alert(clone.greet()); // Not OK, although compiler won't spot it

clone.name = 'Steve';
clone.example.type = 'SteveType';

alert(customer.name + ' ' + customer.example.type); // David SteveType

选项3:Object.create

属性:继承 方法:继承 深度复制:浅继承(深度更改同时影响原始和克隆)

var clone = Object.create(customer);
    
alert(clone.name + ' ' + clone.example.type); // David DavidType
alert(clone.greet()); // OK

customer.name = 'Misha';
customer.example = new Example("MishaType");

// clone sees changes to original 
alert(clone.name + ' ' + clone.example.type); // Misha MishaType

clone.name = 'Steve';
clone.example.type = 'SteveType';

// original sees changes to clone
alert(customer.name + ' ' + customer.example.type); // Misha SteveType

选项4:深度复制功能

属性:是的 方法:没有 深度复制:是的

function deepCopy(obj) {
    var copy;

    // Handle the 3 simple types, and null or undefined
    if (null == obj || "object" != typeof obj) return obj;

    // Handle Date
    if (obj instanceof Date) {
        copy = new Date();
        copy.setTime(obj.getTime());
        return copy;
    }

    // Handle Array
    if (obj instanceof Array) {
        copy = [];
        for (var i = 0, len = obj.length; i < len; i++) {
            copy[i] = deepCopy(obj[i]);
        }
        return copy;
    }

    // Handle Object
    if (obj instanceof Object) {
        copy = {};
        for (var attr in obj) {
            if (obj.hasOwnProperty(attr)) copy[attr] = deepCopy(obj[attr]);
        }
        return copy;
    }

    throw new Error("Unable to copy obj! Its type isn't supported.");
}

var clone = deepCopy(customer) as Customer;

alert(clone.name + ' ' + clone.example.type); // David DavidType
// alert(clone.greet()); // Not OK - not really a customer

clone.name = 'Steve';
clone.example.type = 'SteveType';

alert(customer.name + ' ' + customer.example.type); // David DavidType