C# 是 TypeScript 的最佳替补？
TypeScript非常优秀。它完美地结合了强类型和快速开发，因此非常好用，我在许多情况下都会默认选择这个库。但是，世上没有完美的语言，有些情况下TypeScript并不是最合适的工具：
-
性能至关重要（例如实时通信、视频游戏） -
需要与原生代码（如C/C++或Rust）交互 -
需要更严格的类型系统（例如金融系统）
TypeScript 就是添加了 C# 的 JavaScript
C#和TypeScript的相似之处
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async/await -
lambda表达式和函数式数组方法 -
用于处理空的操作符（?，!，??） -
解构 -
命令行界面（CLI）
async/await
async function fetchAndWriteToFile(url: string, filePath:string): Promise<string> {// fetch() returns aPromiseconst response = awaitfetch(url);const text = awaitresponse.text();// By the way, we'reusing Deno (https://deno.land)awaitDeno.writeTextFile(filePath, text);return text;}
using System.IO;using System.Net.Http;using System.Threading.Tasks;async Task<string> FetchAndWriteToFile(string url, stringfilePath) {// HttpClient.GetAsync()returns a Taskvar response = await newHttpClient().GetAsync(url);var text = awaitresponse.Content.ReadAsStringAsync();awaitFile.WriteAllTextAsync(filePath, text);return text;}
JavaScript API |
等价的C# API |
Promise.all() |
Task.WaitAll() |
Promise.resolve() |
Task.FromResult() |
Promise.reject() |
Task.FromException() |
Promise.prototype.then() |
Task.ContinueWith() |
new Promise() |
new TaskCompletionSource() |
Lambda表达式和函数式数组方法
const months = ['January', 'February', 'March', 'April'];const shortMonthNames = months.filter(month => month.length< 6);const monthAbbreviations = months.map(month =>month.substr(0, 3));const monthStartingWithF = months.find(month => {returnmonth.startsWith('F');});
using System.Collections.Generic;using System.Linq;var months = new List<string> {"January","February", "March", "April"};var shortMonthNames = months.Where(month => month.Length <6);var monthAbbreviations = months.Select(month =>month.Substring(0, 3));var monthStartingWithF = months.Find(month => {returnmonth.StartsWith("F");});
JavaScript API |
等价的C# API |
Array.prototype.filter() |
Enumerable.Where() |
Array.prototype.map() |
Enumerable.Select() |
Array.prototype.reduce() |
Enumerable.Aggregate() |
Array.prototype.every() |
Enumerable.All() |
Array.prototype.find() |
List.Find() |
Array.prototype.findIndex() |
List.FindIndex() |
处理空操作符
| Feature name | Syntax | Documentation links |
|---|---|---|
| Optional properties | property? | TS ：https://www.typescriptlang.org/docs/handbook/2/objects.html#optional-properties C#：https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/nullable-reference-types |
| Non-null assertion | object!.property | TS：https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-0.html#non-null-assertion-operator C#：https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-forgiving |
| Optional chaining | object?.property | JS ：https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining C#：https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/member-access-operators#null-conditional-operators--and- |
| Nullish coalescing | object ?? alternativeValue | JS：https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing_operator C#：https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-coalescing-operator |
解构
const author = { firstName: 'Kurt', lastName: 'Vonnegut' };// Destructuring an object:const { firstName, lastName } = author;const cityAndCountry = ['Indianapolis', 'United States'];// Destructuring an array:const [city, country] = cityAndCountry;
using System;var author = new Author("Kurt", "Vonnegut");// Deconstructing a record:var (firstName, lastName) = author;var cityAndCountry = Tuple.Create("Indianapolis","United States");// Deconstructing a tuple:var (city, country) = cityAndCountry;// Define the Author record used aboverecord Author(string FirstName, string LastName);
命令行界面（CLI）
mkdir app && cd app# Create a new console application# List of available app templates:https://docs.microsoft.com/dotnet/core/tools/dotnet-newdotnet new console# Run the appdotnet run# Run tests (don't feel bad if you haven't written those)dotnet test# Build the app as a self-contained# single file application for Linux.dotnet publish -c Release -r linux-x64
基本功能（类、泛型、错误和枚举）
import { v4 as uuidv4 } from'https://deno.land/std/uuid/mod.ts';enum AccountType {Trial,Basic,Pro}interface Account {id: string;type: AccountType;name: string;}interface Database<T> {insert(item: T):Promise;get(id: string):Promise<T>;}class AccountManager {constructor(database:Database<Account>) {this._database =database;}asynccreateAccount(type: AccountType, name: string) {try {const account = {id: uuidv4(),type,name;};awaitthis._database.insert(account);} catch (error) {console.error(`Anunexpected error occurred while creating an account. Name: ${name}, Error:${error}`);}}private _database:Database<Account>;}
using System;using System.Threading.Tasks;enum AccountType {Trial,Basic,Pro}record Account(string Id, AccountType Type, string Name);interface IDatabase<T> {Task Insert(T item);Task<T> Get(stringid);}class AccountManager {publicAccountManager(IDatabase<Account> database) {_database = database;}public async voidCreateAccount(AccountType type, string name) {try {var account = newAccount(Guid.NewGuid().ToString(),type,name);await_database.Insert(account)} catch (Exceptionexception) {Console.WriteLine($"An unexpected error occurred while creating anaccount. Name: {name}, Exception: {exception}");}}IDatabase<Account>_database;}
C#的其他优势
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与原生代码结合更容易 -
事件 -
其他功能
与原生代码结合
int countOccurrencesOfCharacter(char *string, char character) {int count = 0;for (int i = 0;string[i] != '\0'; i++) {if (string[i] ==character) {count++;}}return count;}
using System;using System.Runtime.InteropServices;var count = MyLib.countOccurrencesOfCharacter("C# is prettyneat, eh?", 'e');// Prints "3"Console.WriteLine(count);class MyLib {// Just placeMyLibraryName.so in the app's bin folder[DllImport("MyLibraryName")]public static externint countOccurrencesOfCharacter(string str, char character);}
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将指针作为IntPtr传给原生对象 -
利用GetFunctionPointerForDelegate()将C#方法作为函数指针传给原生函数 -
使用Marshal.PtrToStringAnsi()将C字符串转换为C#字符串 -
转换结构和数组
事件
class Connection {// AnAction<string> is a callback that accepts a string parameter.public eventAction<string> MessageReceived;}
var connection = new Connection();connection.MessageReceived += (message) => {Console.WriteLine("Message was received: " + message);};
// Raise the MessageReceived eventMessageReceived?.Invoke(message);
其他优势
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性能：C#很快。C#的ASP.NET Web框架一直在Techempower的评测中名列前茅，而C#的.NET CoreCLR运行时的性能每个主要版本都在提高。C#拥有优良性能的原因之一是，通过使用结构而不是类，应用程序可以最小化甚至完全消除垃圾回收。因此，C#在视频游戏编程中非常流行。 -
游戏和混合现实：C#是游戏开发最流行的语言之一，像Unity、Godot甚至Unreal游戏引擎都使用了C#。C#在混合现实中也很流行，因为VR和AR应用程序都是用Unity编写的。 -
由于C#拥有第一方库、工具和文档，因此一些任务非常容易实现，比如，在C#中创建gRPC客户端要比TypeScript方便得多。相反，在Node.js中使用TypeScript时，就必须找出正确的模块和工具的组合，才能正确地生成JavaScript gRPC客户端，以及相应的TypeScript类型。 -
高级功能：C#有许多其他语言没有的功能，如运算符重载、析构函数等。
总结
最高层的语言，开发速度最快
性能并非最佳，但适用于大多数应用
不太适合与原生代码结合
仍然是高级语言，支持垃圾回收，所以很容易使用，尽管并不如TypeScript那么容易。
从速度和内存占用量来看，其性能都优于 TypeScript
最重要的是，能够与底层很好地结合
C++
开发难度较大（例如需要手动内存管理），因此开发速度会慢很多
但运行时的性能最佳！而且随处可用，能与许多已有的软件相结合
很像C#，而且标准库很好，但也有许多陷阱（大多数与内存管理有关）。我更希望使用Rust，因为它的内存安全性更好，但我的许多工作都要与已有的C++代码结合，因此使用C++会更容易。
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