Upgrading to TypeScript 5.5

Upgrading to TypeScript 5.5 brings significant improvements to your development workflow. This version introduces new features, performance enhancements, and better integrations with tools and frameworks. This guide will walk you through upgrading to TypeScript 5.5, using its new features, configuring your environment, resolving migration issues, and optimizing performance.

Upgrading Your Project to TypeScript 5.5

To update your project to TypeScript 5.5, follow these steps:

1. Update TypeScript in your project:

npm install --save-dev typescript@latest
# or
yarn add --dev typescript@latest

2. Update your tsconfig.json file with TypeScript 5.5 settings:

{
  "compilerOptions": {
    "target": "ES2020",
    "lib": ["ES2020", "DOM"],
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "strict": true,
    "skipLibCheck": true
  }
}

3. Verify your upgrade by running:

npx tsc --version
npx tsc

TypeScript versions have specific compatibility requirements with different Node.js versions. Make sure your project uses a compatible Node.js version with TypeScript 5.5.

For projects using Convex, this upgrade enhances your type safety and development experience when building backend functions.

Using New Features in TypeScript 5.5

TypeScript 5.5 brings several new features and improvements that can enhance your development workflow:

Overview of New Features

• Tuple Variance Improvements: These improvements allow more flexible manipulation of tuple types.

type ReadOnlyTuple = readonly [number, string];

function processTuple(tuple: ReadOnlyTuple) {
  console.log(tuple[0]); // Safe operation
}

const myTuple: [number, string] = [1, "hello"];
processTuple(myTuple); // Works due to improved variance

• Enhanced const Assertions: These provide stronger guarantees when using constants.

const point = <const>[10, 20];
point[0] = 30; // Error: Cannot assign to '0' because it is a read-only property

• Improved Type Inference: TypeScript 5.5 enhances type inference capabilities, making code more generics<T> more intuitive to use.

function identity<T>(value: T): T {
  return value;
}

const result = identity("hello"); // Type is inferred as string

• Better Error Messages: TypeScript 5.5 provides clearer error messages that help you understand and fix type issues faster.

TypeScript's utility types are even more useful with TypeScript 5.5's improved type system. The satisfies operator works seamlessly with these enhancements.

If you're using Convex, these improvements make end-to-end type safety even more robust across your application.

Configuring TypeScript 5.5 in Your Development Environment

Properly configuring TypeScript 5.5 is crucial for maximizing its benefits.

For larger projects, consider using project references to break down your codebase into smaller parts:

{
  "references": [
    { "path": "./tsconfig.shared.json" },
    { "path": "./tsconfig.server.json" },
    { "path": "./tsconfig.client.json" }
  ]
}

Project references work well with extends for reusing configuration between projects.

Editor Integration

TypeScript 5.5 works seamlessly with modern code editors. Configure your IDE to use the project's TypeScript version for consistent behavior:

• VS Code: Add "typescript.tsdk": "node_modules/typescript/lib" to settings.json
• WebStorm: Enable "Use TypeScript from node_modules directory" in preferences

Resolving Common Migration Issues

When upgrading to TypeScript 5.5, you might encounter a few challenges. Here are solutions to the most common issues:

Breaking Changes and Compatibility

TypeScript 5.5 includes some breaking changes that might affect your codebase:

// Before TypeScript 5.5
const items = [1, 2, 3] as const;
// TypeScript 5.5 offers an alternative
const items = <const>[1, 2, 3];

If you use decorators in your project, test them thoroughly after upgrading, as decorator behavior might have subtle changes.

Third-Party Libraries

Some libraries might not be compatible with TypeScript 5.5 yet. To address this:

1. Check for updated types: npm update @types/your-library
2. Add type override files in a typings directory if necessary
3. Use the skipLibCheck: true compiler option as a temporary measure

Module Resolution

TypeScript 5.5 refines the module resolution strategy. If you encounter import errors:

{
  "compilerOptions": {
    "moduleResolution": "NodeNext",

    "module": "NodeNext"
  }
}

Projects using Convex's validation system will benefit from TypeScript 5.5's improved type checking. Ensure your validators and types are updated to take advantage of the new features.

Improving TypeScript 5.5 Performance

TypeScript 5.5 offers significant performance improvements over previous versions, but you can further optimize your development workflow with these strategies:

Build Performance Optimizations

TypeScript 5.5's incremental builds can dramatically reduce compilation time:

{
  "compilerOptions": {
    "incremental": true,
    "composite": true,
    "tsBuildInfoFile": "./buildcache/.tsbuildinfo"
  }
}

For large projects, use project references to build only what's changed:

{
  "references": [
    { "path": "./packages/core" },
    { "path": "./packages/ui" }
  ]
}

Type Checking Optimizations

Improve type-checking performance with these settings:

{
  "compilerOptions": {
    "skipLibCheck": true,
    "types": ["node"]
  }
}

TypeScript array operations are faster with TypeScript 5.5's improved type inference. Similarly, TypeScript filter operations benefit from these optimizations.

Editor Performance

Configure your editor settings to enhance performance:

• Disable automatic type acquisition
• Use workspace version of TypeScript
• For large files, consider disabling real-time type checking

Using TypeScript 5.5 with Popular Frameworks

TypeScript 5.5 integrates smoothly with major frameworks, enhancing type safety and developer experience across your tech stack.

React and TypeScript 5.5

TypeScript 5.5 improves the development experience with React through better type inference:

// Function components with improved inference
const Button = ({ onClick, children }: { onClick: () => void, children: React.ReactNode }) => {
  return <button onClick={onClick}>{children}</button>;
};

// Improved type checking for props
type ButtonProps = {
  variant?: 'primary' | 'secondary';
  size?: 'sm' | 'md' | 'lg';
};

When working with React TypeScript projects, TypeScript 5.5's enhanced type checking makes component props more predictable.

Angular and TypeScript 5.5

Angular projects benefit from TypeScript 5.5's improved decorator support:

@Component({
  selector: 'app-root',
  template: `<h1>{{title}}</h1>`
})
export class AppComponent {
  title = 'My App';
}

Decorators are used extensively in Angular applications, making TypeScript 5.5's improvements particularly valuable.

Backend Frameworks

For Node.js backends, TypeScript 5.5 enhances type definitions for popular frameworks:

// Express with TypeScript 5.5
import express from 'express';
const app = express();

app.get('/', (req, res) => {
  res.send('Hello World!');
});

If you're building apps with Convex, TypeScript 5.5's enhanced type safety helps prevent errors in your backend functions and database schema.

Express TypeScript applications can leverage the improved type inference in request and response objects

Solving TypeScript 5.5 Compilation Errors

When working with TypeScript 5.5, you might encounter specific compilation errors. Here's how to tackle the most common ones:

Type Compatibility Errors

TypeScript 5.5 has stricter type checking, which might cause previously working code to show errors:

// Error: Type 'string | undefined' is not assignable to type 'string'
function greeting(name?: string): string {
  return "Hello, " + name; // Error
}

// Fix: Add a check or default value
function greeting(name?: string): string {
  return "Hello, " + (name || "guest");
}

typeof checks may need updating to handle the stricter type system.

Union Type Errors

union types might require more explicit handling:

// Error with discriminated unions
type Action = 
  | { type: 'ADD', payload: number }
  | { type: 'SUBTRACT', payload: number };

function reducer(action: Action) {
  // TypeScript 5.5 may require more explicit checks
  if (action.type === 'ADD') {
    return action.payload; // TypeScript knows payload is number
  }
  return -action.payload;
}

Module Import Errors

If you encounter module resolution issues:

{
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      "@/*": ["src/*"]
    }
  }
}

Final Thoughts about TypeScript 5.5

Upgrading to TypeScript 5.5 is a worthwhile investment for any TypeScript project. The new features improve code quality, the optimized compiler speeds up development, and the enhanced type system catches more errors before runtime.

By following the steps in this guide, you can:

• Smoothly migrate your existing codebase to TypeScript 5.5
• Take advantage of improved tuple handling and type inference
• Configure your environment for optimal performance
• Resolve common migration issues
• Integrate with modern frameworks