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RuleRoster

Source-backed platform rule

Deno local ESM import file-extension requirement

Deno requires the full file extension on local ECMAScript module import specifiers and does not allow it to be omitted.

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Direct answer

What is the rule?

For ECMAScript modules in Deno, local import specifiers must include the full file extension; it cannot be omitted. This rule is scoped to local ESM imports and does not assert requirements for package specifiers, URLs, CommonJS, import-map keys, or arbitrary API strings.

Scope
Deno runtime, module, dependency-integrity, and pack rules
Human verified
August 14, 2026
Source checked
September 3, 2026

Published evidence

Rule details

Local ECMAScript module specifiers

Local ECMAScript module import specifiers must include the full file extension, and it cannot be omitted. This scope is limited to local ESM imports; it does not broaden to package specifiers, URLs, CommonJS, import-map keys, or arbitrary API strings.

Applicability

Service: Deno. Rule group: module-resolution. Scope is limited to this exact topic and its source-stated qualifiers.

Evidence trail

Official sources

Attribution and license

Deno documentation by the Deno authors, Copyright (c) 2018-2024 the Deno authors. Source: https://github.com/denoland/docs/tree/aa772cfbe4455e2a3ef86e9f4df584d41523c0f9. Licensed under the MIT License: https://github.com/denoland/docs/blob/aa772cfbe4455e2a3ef86e9f4df584d41523c0f9/LICENSE. Modified by RuleRoster: RuleRoster extracted and restructured facts into typed rule fields and concise answers. Verified 2026-08-14. No endorsement by Deno or the Deno authors is implied. Project names and marks remain descriptive source identifiers only.

Interpretation and accountability

Before you act

  1. Confirm that the scope matches your case.
  2. Keep recommendations, enforced limits, exceptions, and unstated details distinct.
  3. Open the official source before relying on the rule for a consequential decision.

Record dates

Published
August 15, 2026
Human verified
August 14, 2026
Source checked
September 3, 2026
Review due
September 10, 2026

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