ScriptsApr 11, 2026·1 min read

TypeScript — JavaScript with Syntax for Types

TypeScript is a superset of JavaScript that adds static types, interfaces, generics, and modern ES features, compiled down to plain JavaScript. Created by Anders Hejlsberg at Microsoft. Used by Airbnb, Slack, Asana, and a huge share of modern web projects.

SC
Script Depot · Community
Quick Use

Use it first, then decide how deep to go

This block should tell both the user and the agent what to copy, install, and apply first.

# Install globally
npm i -g typescript

# Or in a project
npm i -D typescript
npx tsc --init

Example:

// user.ts
interface User {
  id: number;
  email: string;
  role: "admin" | "user";
}

function greet(user: User): string {
  return `Hello, ${user.email} (${user.role})`;
}

const me: User = { id: 1, email: "w@tokrepo.com", role: "admin" };
console.log(greet(me));

Compile:

npx tsc                      # Compile once
npx tsc --watch              # Watch mode
npx tsc --noEmit             # Type-check only

tsconfig.json essentials:

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "declaration": true,
    "outDir": "dist"
  },
  "include": ["src/**/*"]
}
Intro

TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. Designed by Anders Hejlsberg (also creator of C# and Turbo Pascal) at Microsoft. First released in 2012, now used in most large-scale web projects. TypeScript makes JavaScript scalable for teams and big codebases by catching type errors at compile time and providing world-class IDE autocomplete and refactoring.

What TypeScript Does

  • Static types — interfaces, type aliases, unions, intersections
  • Generics — parameterized types for reusable code
  • Type inference — infer types from values and signatures
  • Type narrowing — refine types via checks (typeof, instanceof, discriminators)
  • Utility types — Partial, Required, Pick, Omit, Record, Awaited
  • Declaration files — .d.ts for typing existing JS libraries
  • Module resolution — classic, node, bundler strategies
  • JSX support — TSX for React, Vue, Solid
  • Project references — incremental builds across packages
  • Strict mode — strict null checks, no implicit any

Architecture

TSC compiler written in TypeScript itself. Parses source to AST, performs type checking using a structural type system, then emits JavaScript. Language Server (tsserver) powers IDE features via LSP.

Self-Hosting

Language tool, ships via npm.

Key Features

  • Structural type system
  • Type inference
  • Generics
  • Discriminated unions
  • Utility types
  • Declaration files for JS libraries
  • JSX/TSX support
  • Project references
  • Incremental builds
  • Rich LSP integration

Comparison

Language Types Compiles To Runtime
TypeScript Static + inference JavaScript Node/Browser/Bun/Deno
Flow Static JavaScript Same
Hegel Static JavaScript Same
ReScript Static JavaScript Same
PureScript Static JavaScript Same
Elm Static JavaScript Browser

常见问题 FAQ

Q: 什么时候用 TypeScript？ A: 任何 JS 项目超过 1000 行、团队规模 > 1、长期维护。小脚本可以不用。

Q: Strict 模式必须开吗？ A: 强烈建议。关掉严格模式等于放弃 TypeScript 的核心价值。可以用 @ts-expect-error 标注临时例外。

Q: 编译慢？ A: v5+ 引入 project references 和增量构建。大项目用 tsc -b 构建模式。也可用 swc、esbuild 只做转换跳过类型检查（配合 tsc --noEmit 单独检查）。

来源与致谢 Sources

Discussion

Sign in to join the discussion.
No comments yet. Be the first to share your thoughts.

Related Assets

Elixir — Dynamic Functional Language for Scalable Apps

Elixir is a dynamic, functional language for building scalable and maintainable applications. Runs on the battle-tested Erlang virtual machine (BEAM) with the same fault-tolerant, distributed, soft real-time properties. The language behind Phoenix framework and LiveView.

Script Depot

Kotlin — Modern Statically Typed Language for JVM and Beyond

Kotlin is a statically typed, general-purpose programming language developed by JetBrains. Runs on the JVM, Android, native, WebAssembly, and JS targets. Officially endorsed by Google as the preferred language for Android development.

Script Depot

Flutter — Google Cross-Platform UI Toolkit for Beautiful Apps

Flutter is Google cross-platform UI toolkit for crafting beautiful, natively compiled applications for mobile, web, desktop, and embedded devices from a single codebase. Powered by the Dart language and the Skia rendering engine (now Impeller).

Script Depot
◈Home🔍Search👤Me