Lets say I have a typescript file Utils with a bunch of exported functions:
export function utilOne(){}
export function utilTwo(){}
I added index.d.ts file to this folder where I export * from the Utils file:
export * from './Utils';
In my other classes I'd like to access functions utilOne and utilTwo via utils namespace, like:
utils.utilOne();
I know that I can import it like this:
import * as utils from "./Utils";
However, as I will be using utils a lot, I would like to be able to export utils in a namespace, something like:
export {* as utils} from './Utils'; // this doesn't work
and then use:
import * from "./Utils";
However the export {* as utils} doesn't work. I could put all the functions of Utils to a module "utils" and export it, but I am not sure if this is a good practice. Is there a proper way to do this?
Use named exports to export multiple functions in TypeScript, e.g. export function A() {} and export function B() {} . The exported functions can be imported by using a named import as import {A, B} from './another-file' . You can have as many named exports as necessary in a single file.
Use named exports to export a function in TypeScript, e.g. export function sum() {} . The exported function can be imported by using a named import as import {sum} from './another-file' . You can use as many named exports as necessary in a single file.
To export multiple functions in JavaScript, use the export statement and export the functions as an object. Alternatively, you can use the export statement in front of the function definitions. This exports the function in question automatically and you do not need to use the export statement separately.
The export as namespace form creates a global variable so it can be used without importing, but you may still import it with the import { name } from "some-library" form of import.
import * from
No. Global imports are considered bad practice even in languages that support them. (e.g. python Why is "import *" bad?)
JavaScript / TypeScript doesn't support it. After all its pretty useful to see foo.bar
and know that bar is coming from foo
instead of bar
and having no clue where bar is coming from (without cloning and analyzing the whole project). 🌹
Since TC39/ecma 262 the feature you probably need was merged. So now you can export the module itself like this:
// module.ts
interface Foo{
bar: string;
}
function A(){
}
function B(){
}
export * as MyModule from './module';
And then use it like a module that contains his own context:
import {MyModule} from './module';
type MyType = MyModule.Foo;
MyModule.A();
MyModule.B();
Seems to me it depends on TS version and webpack if you are using it. For me it's webpack 5 and TS v4.1.2 works good. Did not check tree-shaking yet, but looks it should work fine.
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