TSLint in 2019
TSLint and ESLint today
Today, TSLint is de facto the standard linter for TypeScript repositories and for the TypeScript implementation itself. The TSLint ecosystem consists of a core rule set together with community-maintained custom rule and configuration packages.
TypeScript + ESLint
- Uniting the community: At their core, ESLint and TSLint have the same purpose: to provide an excellent code linting experience with a strong core rule set and extensive plugin points. Now that TypeScript parsing is available within ESLint, we believe it’s best for the communities to standardize, rather than to maintain fragmentation through competing tools.
- More performant analysis infrastructure: The ESLint API allows for more efficient implementations of certain classes of checks. Although it would be possible to refactor TSLint’s APIs, it seems prudent to leverage ESLint’s architecture and focus our development resources elsewhere.
- Investment hypothesis: Within Palantir, TSLint encodes our tradecraft for the TypeScript language; as such, its feature set and architecture have matured and reached a steady state. It has thus been hard for us to justify the level of commitment needed to keep up with community contributions and demands.
Palantir will support the TSLint community by providing a smooth transition path to ESLint via a range of feature and plugin contributions (shout out to James Henry and other contributors there for getting it started!), for instance:
- Support & documentation for writing ESLint rules in TypeScript: See this typescript-eslint issue thread.
- Testing infrastructure in typescript-eslint: ESLint’s built-in rule tester is hard to use and the test case syntax is hard to read. We’d like to bring something like TSLint’s testing infrastructure to this project to ensure there are no regressions in the TSLint rule development experience.
- Semantic, type-checker-based rules: Porting over and adding new rules which use TypeScript language services.
Once we consider ESLint feature-complete w.r.t. TSLint, we will deprecate TSLint and help users migrate to ESLint; our primary tasks until then include:
- Continued TSLint support: The most important maintenance task in TSLint is ensuring its compatibility with new compiler versions and features.
- TSLint → ESLint compat package: Once the ESLint static analysis checks are on a par with TSLint, we’ll publish an eslint-config-palantir package, a drop-in ESLint replacement for our TSLint rule set.
We’ve loved seeing TypeScript and TSLint grow in adoption over the past few years, and we’re excited to contribute to the even more impactful future of TypeScript in the Web development ecosystem! Please get in touch with us by commenting on this post or via GitHub Issues if you have questions or concerns, or if you would like to help.