Did you know with Typescript, you can do type-only imports?
import type { Foo } from "./types"
If the file exports both types and values, you can use two separate import statements like this:
import type { Foo } from "./types";
import { BarValue } from "./types"
But is it possible to import a type and a value together in one statement?
If your bundler requires it, then you should use the import type syntax. According to information from the official documentation:
...this allows non-TypeScript transpilers like Babel, swc or esbuild to determine which imports can be safely removed.
In cases where this is not necessary, simply using import will suffice:
import { Foo, BarValue } from "./types";
However, if you find that you do require it, starting from version 4.5, you have the option to use the type prefix on specific parts of the import:
import { type Foo, BarValue } from "./types";
For what it's worth, I frequently use regular import statements that bring in both types and values without any issues, even in projects with isolatedModules: true set in the tsconfig.json. The bundlers I work with (mostly Vite, but also Webpack) do not necessitate the use of import type.
To confirm, I conducted a test in a brand-new project:
tsconfig.json
{
"compilerOptions": {
"isolatedModules": true
}
}
types.ts
export type Foo = {
a: number;
};
export const BarValue = 42;
main.ts:
import { Foo, BarValue } from "./types";
const a: Foo = {
a: 42,
};
console.log(BarValue);
console.log(a);
The tsc command executed successfully and generated the expected types.js and main.js files. I verified that it was able to output either ESM or CommonJS with the standard import statement (without including the type portion).
I found success with this solution in the latest version of TypeScript:
import { FooType, BarValue } from "./types";
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