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Dependency Version Upgrades

Babel​

Our published packages only depend on @babel/* packages as devDependencies. You can generally upgrade those dependencies with:

  1. yarn add -D @babel/code-frame @babel/core @babel/eslint-parser @babel/parser @babel/types
  2. npx nx run ast-spec:test -u

The fixtures under packages/ast-spec/ describe how the files are parsed under both Babel and our (TSESTree) parser.

ESLint​

The typescript-eslint repository contains four kinds of version ranges for the eslint package:

  • Integration tests: Pinned to our lowest supported ESLint version
  • Packages with a * peerDependency version: These fall back to the explicit peerDependency versions
  • Packages with explicit peerDependency versions: The full range of supported ESLint major versions
  • Root package.json's' devDependency: A relatively recent release, used only for repository development
tip

Whenever you discover any new areas of work that are blocked by dropping an old ESLint version, such as new ESLint API deprecations, add a TODO comment that will be caught by the regular expressions under Removing Support for an Old ESLint Version.

Adding Support for a New ESLint Version​

  1. Upgrade the root package.json devDependency to the latest ESLint
  2. Add the new major version to the explicit peerDependency versions
  3. Check eslint-visitor-keys for a new version to be upgraded to as well.
  4. Update Users > Dependency Versions > ESLint

Removing Support for an Old ESLint Version​

  1. Increase the integration tests to the next lowest supported major version (*.0.0)
  2. Remove the old major versions from packages with explicit peerDependency versions
  3. Search for source code comments (excluding CHANGELOG.md files) that mention a now-unsupported version of ESLint.
    • For example, to remove support for v5, searches might include:
      • /eslint.*5/i
      • /todo.*eslint.*5/i
      • /todo.*eslint/i
  4. Update Users > Dependency Versions > ESLint

See chore: drop support for ESLint v6 for reference.

Node​

The typescript-eslint repository contains three kinds of version ranges for Node:

  • .github/workflows/ci.yml's PRIMARY_NODE_VERSION: Set to the highest Node version we support
  • node-version: Set to a tuple of our [lowest, highest] supported versions for our unit tests in CI
  • engines field in all package.jsons: explicitly lists all supported Node ranges

Change those numbers accordingly when adding support for a new Node version or removing support for an old Node version.

See feat: drop support for node v12 + chore: test node v14 on ci.yml for reference.

TypeScript​

Adding Support for a New TypeScript Version​

We generally start the process of supporting a new TypeScript version just after the first beta release for that version is made available.

  1. Create and pin an issue with a title like TypeScript X.Y Support, accepting prs, AST, dependencies, and New TypeScript Version labels, and the following contents:

    1. A link to the TypeScript X.Y Iteration Plan issue from the Microsoft issue tracker

    2. The following text:

      This issue is just to track all of the new features and their implementation state in this project.
      As with all releases, we will not necessarily support all features until closer to the full release when everything the features are stabilised.

      _Please be patient._ ❤️

    3. A heading starting with 🔲 for each new TypeScript feature called out in the iteration plan that will impact us

    4. A heading titled 🔲 lib.d.ts Updates and the content We will need to regenerate our types within scope-manager

    5. A heading titled Other changes with no impact to us containing a list of other changes that we don't believe will impact us

  2. At this stage, it's fine to send and/or review PRs that implement necessary features, but wait to merge them until the new TypeScript version's RC is released

    • Whenever a PR is created, add (#1234) to its respective heading, and change the heading's emoji from 🔲 to 🏗
    • Search for expectBabelToNotSupport to see how to support syntaxes not yet supported by Babel

  3. Once the TypeScript RC version is released, start merging PRs

    • Whenever a PR is merged, change the respective heading's emoji from 🏗 to ✅

  4. Create a PR with a title like feat: update TypeScript to X.Y-rc and the following changes:

    • In the root package.json, add || X.Y.2-rc2 to the dependency on typescript
    • In the root package.json, change the devDependency on typescript to ~X.Y.2-rc2
    • Change the SUPPORTED_TYPESCRIPT_VERSIONS constant's < version to the next version of TypeScript
    • Change the SUPPORTED_PRERELEASE_RANGES constant to equal ['X.Y.2-rc']
    • Rename and update patches/typescript* to the new TypeScript version
    • Run yarn generate-lib to update scope-manager

  5. Once all PRs needed for the RC update PR are merged, merge the RC update PR

  6. Once TypeScript releases the stable X.Y version, create and merge a PR with a title like chore: bump TypeScript from X.YRC to X.Y and the following changes:

    • In the root package.json, remove || X.Y.2-rc2 from the dependency on typescript, and bump its < version to the next version of TypeScript
    • In the root package.json, change the devDependency on typescript to ~X.Y.3
    • Rename and update patches/typescript* to the new TypeScript version
    • Any other changes made necessary due to changes in TypeScript between the RC version and stable version
    • Update the supported version range in Users > Dependency Versions

  7. Update Users > Dependency Versions > TypeScript

  8. Send a PR that updates this documentation page to point to your newer issues and PRs

    • Also update any of these steps if you go with a different process

See for reference (caveat: these don't follow the exact process described here):

Removing Support for an Old TypeScript Version​

A single PR can remove support for old TypeScript versions as a breaking change:

  1. Update the root package.json devDependency
  2. Update the SUPPORTED_TYPESCRIPT_VERSIONS constant in warnAboutTSVersion.ts
  3. Update the versions constant in version-check.ts
  4. Update Users > Dependency Versions > TypeScript
  5. Search for source code comments (excluding CHANGELOG.md files) that mention a now-unsupported version of TypeScript.
    • For example, to remove support for v4.3, searches might include:
      • 4.3
      • /is.*4.*3/i
      • /semver.*4.*3/i
      • /semver.satisfies/
      • /todo.*ts/i
      • /todo.*typescript/i

See feat: bump minimum supported TS version to 4.2.4.