CODEWITHSUNDEEP
typescript
Shivanshu Goyal
Shivanshu Goyal

Reputation: 1452

Typescript doesn't complain about missing imports

Contents of foo.ts:

let a: Person = new Person();

Contents of bar.ts:

class Person {}

The tsconfig.json file contains the default set of values created by tsc --init.

I'm using typescript version 2.6.2.

The code above simply compiles with no errors about Person being not defined. If I rename Person to Persons in foo.ts, then it does throw an error saying cannot find name 'Persons'. So it's as if it is automatically importing this file somehow.

Also note that I'm not exporting the Person class in bar.ts. If I do add an export statement, then everything behaves as it should - I get an error saying cannot find name 'Person'.

Does anyone know what's going on here? Is this a user error?

Edit:

Maybe this makes sense in the browser, but to me this behavior makes no sense in a node.js application. Is there a Typescript flag which forbids this behavior?

Upvotes: 12

Views: 3699

Answers (2)

Shivanshu Goyal
Shivanshu Goyal

Reputation: 1452

The compiler flag --isolatedModules will ensure that all .ts files are modules. Once you make foo.ts and bar.ts modules by adding at 1 import or export, then the Person class will not be global anymore.

This, however doesn't solve the following similar issue: https://github.com/Microsoft/TypeScript/issues/18232#issuecomment-359200157

Upvotes: 3

JB Nizet
JB Nizet

Reputation: 692131

Your bar.ts is not a module, since it doesn't have any import nor any export. So it defines a global Person class, that doesn't need to be imported, since it's global. Export it, and TypeScript will complain about the missing import.

Upvotes: 4

Related Questions