How can I force VSCode TypeScript auto-imports to use .ts extension instead of .js?

[fushihara]

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Comment

I was guided here from typescript-language-server/typescript-language-server#1028 , so I’m following up on my question here.

In VSCode 1.105 with TypeScript, auto-completion for symbols sometimes inserts imports with a .js extension and other times with .ts. This inconsistency is problematic for my project.

Example:

• export-a.ts:

export function exportA() {}

• In import-a.ts, when I select the completion for exportA, VSCode may insert either:

import { exportA } from "./export-a.js";

or:

import { exportA } from "./export-a.ts";

My goal is one of the following:

1. A clear, documented rule explaining how the extension is chosen; or
2. A reliable configuration to force one extension (preferably .ts for my project), so the result is deterministic.

Project context:

• tsconfig.json includes "allowImportingTsExtensions": true and "noEmit": true.
• In Node.js v24, importing .ts files works without special flags; rewriting to .js can cause runtime errors.
• I understand some bundlers prefer .js, and that can make sense in other setups. But in this project, I want imports to remain .ts.

Things I’ve observed but can’t fully explain:

• If the active file already contains at least one import ... from "./*.ts", subsequent auto-imports seem more likely to stay as .ts.
• Behavior appears cached until I run Developer: Reload Window.

Questions:

• What is the exact decision logic for choosing .js vs .ts in auto-imports?
• Is there an official setting (VSCode or TypeScript) to always generate .ts (or always .js) for auto-imports?
• If this behavior is intended, can the rule be documented so users can predict and configure it?

[RyanCavanaugh]

In general this is just supposed to work automatically based on your preferences and existing imports. I haven't seen any other reports of this not working as expected, so it seems likely there's something unexpected about your project setup that's causing this to not work. Can you share a repo?

If you need to read the exact algorithm, it's in importFixes.ts

[bwalendz]

Looks like it's working via good old manual typing but it appears that Copilot Completion doesn't include the extension

{
    "emitDeclarationOnly": true,
    "module": "esnext",
    "moduleResolution": "bundler",
    "allowImportingTsExtensions": true
}