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TS1194: Export declarations are not permitted in a namespace

TS1194: Export declarations are not permitted in a namespace

TypeScript is a powerful programming language that builds on JavaScript (a widely used scripting language) by adding static type definitions. This enables developers to catch errors at compile time, making the development process smoother and more predictable. Types are specific classifications of data that determine the operations that can be performed on them. By using types, programmers can define what kind of data can be stored in variables, passed to functions, or included in interfaces.

If you're interested in learning more about TypeScript or want to use AI tools like gpteach to improve your coding skills, I recommend subscribing to my blog for updates and tutorials.

What are Enums?

In TypeScript, enums (short for enumerations) are a special "class" that represents a group of constants. They allow you to define a set of named values, making your code better organized and easier to read. For example:

enum Color {
    Red,
    Green,
    Blue
}

// Usage
let c: Color = Color.Green;
console.log(c); // Output: 1 (the numeric value of Green)
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Enums are particularly useful when you have a set of related values that you want to manage in a type-safe way.

TS1194: Export declarations are not permitted in a namespace.

One common issue developers face when using TypeScript is the error message "TS1194: Export declarations are not permitted in a namespace." This error occurs when you try to use an export statement within a namespace. Namespaces serve as a way to organize code and prevent naming collisions, but they have specific rules regarding exports.

When Does TS1194 Occur?

The error TS1194: Export declarations are not permitted in a namespace. typically arises when you attempt to export a variable, function, or class inside a namespace. Here’s an example that triggers this error:

namespace MyNamespace {
    export class MyClass {
        constructor() {
            console.log('Hello from MyClass');
        }
    }
}
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The code above will produce the error 'TS1194: Export declarations are not permitted in a namespace.' because we're trying to use an "export" keyword in a namespace declaration.

How to Fix TS1194?

To resolve this error, you can remove the export statement from inside the namespace and instead export the entire namespace if needed, like this:

namespace MyNamespace {
    class MyClass {
        constructor() {
            console.log('Hello from MyClass');
        }
    }
}

export { MyNamespace }; // Export the namespace itself
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Now, the namespace contains the class but doesn’t attempt to export it directly, which aligns with TypeScript’s restrictions.

Important to know!

  • Always avoid using the export keyword inside a namespace. Instead, consider exporting the entire namespace if necessary.
  • Use modules instead of namespaces for better module management and clearer code.

Additional Example

Consider the following erroneous code that throws the same TS1194 error:

namespace Shapes {
    export interface Circle {
        radius: number;
    }
}
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To fix it, you can implement a similar solution:

namespace Shapes {
    interface Circle {
        radius: number;
    }
}

export { Shapes }; // Export the Shapes namespace
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FAQ's Section

Q: What is the purpose of namespaces in TypeScript?

A: Namespaces help to organize your code into logical groups and prevent naming conflicts between different parts of your code.

Q: Is it better to use namespaces or modules in TypeScript?

A: It’s generally recommended to use modules instead of namespaces for better scalability and structuring of large applications.

Q: What should I do if my project uses namespaces extensively?

A: If your project already uses namespaces, consider gradually refactoring to modules, as they provide better support for encapsulation and importing/exporting functionalities.

Important to know!

  • Namespaces are a way of grouping related code, but they are not suitable for everything, especially in larger codebases.
  • Consider adopting ES modules (using import/export) as they integrate well with modern JavaScript tooling and concepts.

In summary, the error TS1194: Export declarations are not permitted in a namespace. serves as an important reminder of TypeScript's structure and conventions. By adhering to these practices, you'll ensure a smoother development experience and maintain a clean codebase.

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