Microsoft/TypeScript

Move away from Classic module resolution as default for all module kinds

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#11,434 opened on Oct 6, 2016

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 (8 comments) (10 reactions) (0 assignees)TypeScript (48,455 stars) (6,726 forks)batch import
CommittedEffort: ModerateHelp WantedSuggestion

Description

TypeScript's original module resolution strategy (the Classic resolution strategy) has some strange behavior that apparently doesn't actually reflect any other resolution strategy. It seems strange that those using non-CommonJS emit targets get this behavior by default.

Classic resolution also causes many disk probes during the walk up the project root - assuming that this strategy does eventually succeed in most cases, it seems like most uses could be subsumed by:

  • Using relative paths.
  • Modifying the baseUrl and paths properties in tsconfig.json.

After discussing with @vladima, we think it is worth considering switching the default resolution strategy for all module targets to Node.

Here's what needs to be done:

  • Investigate existing tsconfig.jsons that target esXXXX` and have no explicit/implied resolution strategy.
  • Determine the downstream effects to a change to defaults
  • Determine if this change outweighs the potential breakage
  • Implement if appropriate

Contributor guide

Tech stack
typescript
Domain
toolingdeveloper experience
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
5
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
TypeScript module resolution conceptsNode.js module resolutiontsconfig.json configurationAnalyzing large codebases
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
10
Research direction
Start by reviewing the issue discussion and comments for additional context. Then, investigate existing TypeScript configurations in open source projects that use esXXXX module target and no explicit resolution strategy. Use the TypeScript compiler source code (src/compiler/) to understand current resolution logic. Based on findings, propose a migration plan or backward compatibility strategy. The issue's checklist provides a clear roadmap.