Is there a way to make a file in your typescript file that defines globally accessible types?
I like typescript but find that when i want to be truly type safe I have to explicitly import types from all over the system. It's rather annoying.
To declare a global variable in TypeScript, create a . d. ts file and use declare global{} to extend the global object with typings for the necessary properties or methods.
In Python and MATLAB a global variable can be declared anywhere with the global keyword. Ruby's global variables are distinguished by a ' $ ' sigil.
declare global is used inside a file that has import or export to declare things in the global scope. This is necessary in files that contain import or export since such files are considered modules, and anything declared in a module is in the module scope.
Yes this is possible. You can find all information here: https://www.typescriptlang.org/docs/handbook/declaration-files/templates/global-modifying-module-d-ts.html
The important part is this:
declare global { /*~ Here, declare things that go in the global namespace, or augment *~ existing declarations in the global namespace */ interface String { fancyFormat(opts: StringFormatOptions): string; } }
I found the accepted answer is not working (maybe it is some configuration that needs to be done?). So with some tinkering, I got it to work for me (maybe I also have some weird configuration option? Let me know if it doesn't work and I will remove this answer).
types/global.d.ts
tsconfig.json
and include "*": ["types/*.d.ts"]
under paths
. (You should also be able to directly address the created file if you care to).declare global
or similar.Now you should be good to go to use the types declared in this file (tested with typescript 3.9.6 and 3.7.5).
Example file:
// global.d.ts declare interface Foo { bar: string; fooBar: string; }
What your tsconfig
should look like:
[...] "paths": { "*": ["types/*.d.ts"] }, [...]
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