TS1443: Module declaration names may only use ' or " quoted strings

TypeScript is a strongly typed programming language built on top of JavaScript. It's often referred to as a superset of JavaScript because it extends JavaScript's capabilities by adding features like static typing (a way to define the type of data a variable can hold), type definitions, and interfaces, all while retaining JavaScript's core features and syntax.

In TypeScript, types are a fundamental part of the language. A type can be thought of as a label or blueprint that defines the kind of data a value can hold. Using types ensures that your code is more predictable and reduces runtime errors. For instance:

let name: string = "John"; // 'name' can only hold a string
let age: number = 30; // 'age' can only hold a number

TypeScript enforces these constraints at compile-time, making it easier to catch bugs earlier in the development cycle. If you'd like to learn more about TypeScript or use AI tools like GPTeach to enhance your coding skills, visit GPTeach here.

One concept related to TypeScript's power is interfaces, which act as blueprints for how objects should look. Interfaces make it easier to define the structure of data for maintainability and scalability. For instance:

interface User {
  name: string;
  age: number;
  isAdmin: boolean;
}

const user: User = {
  name: "Alice",
  age: 25,
  isAdmin: true,
};

TS1443: Module declaration names may only use ' or " quoted strings

One common TypeScript issue you'll encounter is the compiler error TS1443: Module declaration names may only use ' or " quoted strings. This error typically appears when writing TypeScript definition files (.d.ts) or when declaring modules incorrectly. It is primarily caused by improper syntax when naming the module declaration.

Breaking Down the Error

The error occurs when the module's declaration name isn't wrapped in single (') or double (") quotes, which is a strict rule in TypeScript. For example, attempting to declare a module with an unquoted or improperly quoted name results in this error.

Here's an example that triggers TS1443: Module declaration names may only use ' or " quoted strings:

declare module my-module {
  // some code here
}

In this snippet, my-module isn't quoted. As per TypeScript's rules for module declaration names, the name must be a valid string literal, wrapped in single or double quotes.

How to Fix the Error

The solution is straightforward: ensure that the module declaration name uses either single or double quotes. Here's the corrected version:

declare module "my-module" {
  // Correct: module name is wrapped in double quotes
  export const myFunction: () => void;
}

You can also use single quotes if that's your code style preference:

declare module 'my-module' {
  // Correct: module name is wrapped in single quotes
  export const myFunction: () => void;
}

Both approaches are equally valid and resolve TS1443: Module declaration names may only use ' or " quoted strings.

Why Does This Error Happen?

The strict requirement for quoted strings in module declarations exists to avoid ambiguity and to improve the consistency of how TypeScript works with module scoping. Without strict rules, the compiler might have trouble differentiating between reserved keywords, object literals, or module names.

Important to Know!

1. The error TS1443: Module declaration names may only use ' or " quoted strings is specific to .d.ts files or custom module declarations.
2. If you are unfamiliar with declaring modules, remember that module declaration files (.d.ts) help TypeScript understand external JavaScript libraries or custom module setups.
3. Always follow this convention when declaring a module for consistency and prevent future issues when working with config files or TypeScript projects.

Example with Full Usage

Suppose you are trying to declare a module for a legacy JavaScript package called "legacy-lib". Here's how you might incorrectly write it:

declare module legacy-lib {
  export function legacyFunction(): string;
}

You'll encounter TS1443: Module declaration names may only use ' or " quoted strings here. To fix it:

declare module "legacy-lib" {
  export function legacyFunction(): string;
}

Important to Know!

1. If you accidentally forget to put quotes around a declaration, the error will prevent your project from compiling successfully, even if everything else is correct.
2. For internal projects, always document custom module declarations properly so that team members can follow this convention.

FAQs

What is the purpose of declaring modules?

Declaring modules (often in .d.ts files) allows TypeScript to understand and provide type safety for external libraries or your custom code. It's common when using JavaScript packages without pre-existing TypeScript typings.

What happens if I ignore this error?

If ignored, your program won't compile, and the IDE support for modules won't work correctly. This small mistake can cause larger issues, such as runtime bugs and misunderstood module imports.

Can I use template literals for module declarations?

No, template literals aren't supported in module declaration names. Always use single or double quotes instead.

Final Thoughts on TS1443: Module declaration names may only use ' or " quoted strings

The error TS1443: Module declaration names may only use ' or " quoted strings is straightforward to resolve but essential to understand when working with TypeScript projects. Properly quoted module declaration names ensure maintainability, minimize errors, and help TypeScript provide better tooling and type safety. By following these best practices, you'll avoid the pitfalls of incorrectly declared modules, and your codebase will be easier to manage and scale efficiently.