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Visual Studio Code – How do I import npm types to Deno?

I’m working in a Deno project that uses the mssql npm package. I can import it like import sql from 'npm:mssql'; and it works. The problem is that I get no types on VS Code. When I type "sql." I get no suggestions and everything I type after has type any.

If I remove that import and instead use import sql from 'npm:@types/mssql'; then I can see suggestions when I type "sql.", but it crashes when I run it because there are no actual values (I get a "Cannot find module …" error).

And if I import both like

import sql from 'npm:mssql';
import sql from 'npm:@types/mssql';

then I get a duplicate identifier error. Is there a way to get both types and values?

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2

Answers


  1. 0

    The problem is that VSCode tries running tsserver for TS-related features, but it is not fully compatible with Deno.

    The easiest solution for VSCode would be simply adding Deno official extension. Then opening the VS Code command palette (normally Ctrl+Shift+P), and running the Deno: Enable command.
    It will run Deno language server, which is fully compatible and also faster than tsserver

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  2. 0

    In a classic TSC based project you can have a separate type resolution root and a source resolution root so you can have code like:

    import sql from 'mssql';
import type { Connection } from 'mssql';

    and this would be resolved both from node_modules and node_modules/@types (assuming @types is set as a type resolution root).

    However according to the docs Deno applies a design principle of no non-standard module resolution, which (I think) means you can’t have varying resolution roots.

    This does result in issues with typescript, but Deno offers a solution in your code by allowing you to have a @ts-types doc declaration. In this case you’d do:

    // @ts-types="npm:@types/mssql"
import sql from 'npm:mssql';

    which will instruct Deno to include type definitions from @types/mssql

    Note: I would imagine IDEs might eventually do this implicitly but as far as I can tell this seems to be the official way of doing it right now.

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