Solved: index.ts’ cannot be compiled under ‘–isolatedModules’ because it is considered a global script file. Add an import, export, or an empty ‘export {}’ statement to make it a module.

This Typescript issue we’re discussing today is characteristic of a key aspect in Typescript’s design and implementation – its interaction with modules. One of the most common compilation errors encountered is `index.ts cannot be compiled under –isolatedModules` because it is considered a global script file. This problem has often led to a widespread misunderstanding in the Typescript community regarding how scripting and module import/export should be done.

Demystifying the Problem

  • The isolatedModules flag feature of Typescript enforces that every file has to be a module. It means that all files should include an import or export statement. But when Typescript comes across a file that lacks this, it throws the above-mentioned error. This occurs because Typescript treats such files as a script rather than a module.


To overcome this hiccup, there are a couple of measures we can take:

  • Add an import or export statement. This makes Typescript recognize it as a module.
  • Alternatively, if there’s nothing to export or import, you can add in an empty export statement like ‘export {}’.
// Adding an Import Statement
import { ModuleName } from "module-location";
// Adding an Export Statement
export { variableOrFunctionName };
// Adding an Empty Export Statement
export {};  

Step by Step Explanation of the Code

1. Import Statement: Using the ‘import’ keyword, we can import a module into the current file. In the example above, we extracted ‘ModuleName’ from its module.

2. Export Statement: This keyword allows us to export a function, variables, etc. from a module. So, in another module, you could use ‘import’ to bring whatever was exported into the current module.

3. Empty Export Statement: This keyword tells Typescript that this is a module even if there’s nothing to export. By adding ‘export {}’, we are exporting an empty object.

Libraries, Functions, and Other Relevant Topics

Typescript Module system

Modules are integral parts of any robust application’s architecture. They play a vital role in achieving well-structured and maintainable code. They provide the concept of encapsulation, which is used to keep the units of code for a project cleanly separated and organized.

The Role of the ‘isolatedModules’ flag

This flag ensures that every Typescript file gets transpiled in isolation without depending on any other file, as Babel does in its compilation process. This flag is required when using Babel for transpiling to guarantee compatibility.

Understanding the process of import and export statements, as well as the use of the ‘isolatedModules’ flag, is of great help when navigating these Typescript compilation issues.

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