How to fix Could not find a declaration file for module 'X' in TypeScript

# General pattern
npm install --save-dev @types/package-name

# Common examples:
npm install --save-dev @types/lodash
npm install --save-dev @types/express
npm install --save-dev @types/node
npm install --save-dev @types/react
npm install --save-dev @types/jquery

// This will now have full type support
import _ from "lodash";
import express from "express";

// types/my-library.d.ts
declare module "my-library" {
  // Export the functions/values you're using
  export function someFunction(arg: string): number;
  export const someValue: string;

  // For default exports
  export default function myLibrary(): void;
}

// types/my-library.d.ts
// Quick workaround - types everything as 'any'
declare module "my-library";

{
  "compilerOptions": {
    "typeRoots": ["./node_modules/@types", "./types"]
  },
  "include": ["src/**/*", "types/**/*"]
}

// types/my-library.d.ts
declare module "my-library" {
  export interface Config {
    timeout: number;
    retries: number;
  }

  export class Client {
    constructor(config: Config);
    connect(): Promise<void>;
    disconnect(): void;
  }
}

{
  "compilerOptions": {
    // Explicitly specify where to find type definitions
    "typeRoots": [
      "./node_modules/@types",
      "./types"
    ],

    // Alternative: specify exact packages to include
    "types": ["node", "react", "lodash"],

    // Ensure proper module resolution
    "moduleResolution": "node",
    "esModuleInterop": true
  },
  "include": [
    "src/**/*",
    "types/**/*"
  ]
}

{
  "compilerOptions": {
    "moduleResolution": "node",
    "esModuleInterop": true
  }
}

{
  "compilerOptions": {
    "skipLibCheck": true
  }
}

# Check installed versions
npm list lodash
npm list @types/lodash

# If versions don't match, install compatible @types
npm install --save-dev @types/[email protected]

# Check package info before installing
npm info @types/package-name versions

// package.json
{
  "dependencies": {
    "express": "^5.0.0"
  },
  "devDependencies": {
    // WRONG - types for Express 4
    "@types/express": "^4.17.0"

    // CORRECT - match major version
    "@types/express": "^5.0.0"
  }
}

// types/package-name.d.ts
// Import from closest version and extend
import type { SomeType } from "@types/package-name-v4";

declare module "package-name" {
  export * from "@types/package-name-v4";
  // Add missing types for v5 features
  export function newV5Feature(): void;
}

# Delete TypeScript build cache
rm -rf node_modules/.cache
rm -rf .tsbuildinfo

# Delete all build output
rm -rf dist build

# Reinstall dependencies
rm -rf node_modules
npm install

# Restart TypeScript server in VS Code
# Cmd/Ctrl + Shift + P → "TypeScript: Restart TS Server"

1. Open command palette (Cmd/Ctrl + Shift + P)
2. Type "TypeScript: Restart TS Server"
3. Press Enter

File → Invalidate Caches → Invalidate and Restart

:CocRestart