Visibility in classes can shift once a new file is imported

Currently, I am encountering a puzzling issue in my angular2 project using typescript. In my main.ts file, which contains a component along with some imports at the start of the file, there is a custom type class (let's call it TypeFoo) located in models/typeFoo.ts. Surprisingly, despite TypeFoo having no imports within typeFoo.ts, it can still be utilized in main.ts without requiring an import statement for typeFoo.ts. This behavior seems strange to me. However, as soon as I introduce an import statement in typeFoo.ts pointing to another file, main.ts starts throwing errors indicating that TypeFoo is no longer accessible. Can someone shed light on why this is happening?

main.ts
--models/typeFoo.ts

class TypeFoo {
    name: string;
}

Answer №1

It's quite interesting that the type TypeFoo can be utilized in main.ts without the need for importing the file directly into main.ts. That certainly raises some eyebrows!

In scenarios where there is no root level import or export, the file is treated as a global file. However, when an import or export is added, it transforms into a module (which is usually preferred).

You can find more information on this topic here: https://basarat.gitbooks.io/typescript/content/docs/project/modules.html

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