ts-helper

This is a simple TypeScript tool we use at Glide for two purposes so far:

1. It finds cyclic imports in our source files. We used to use ESLint's import/no-cycle rule for this, but on our project it's both very slow and sometimes doesn't find existing cycles.
2. It outputs a dependency graph of all the TypeScript source files in our project which we can use for further analysis.

Caveats

We've only implemented as much as we needed to make this work on our codebase, so there might be cases it doesn't support, or on which it crashes on. If you run into such a case, please considering sending us a PR, or at least report the issue with a reproduction.

A few of the things that are missing, in particular:

• We don't respect exclude in the project configuration.
• We only look at import (and export), not require.
• We treat type import calls such as type X = import("foo").Bar as regular "strong" imports.

Usage

-p|--project TS-PROJECT

Adds a project. TS-PROJECT can be either a directory with a tsconfig.json file in it, or the path to a TypeScript config file. ts-helper will add project references recursively, but you can add more than one root project if you need to.

-r|--root SOURCE-FILE

Adds a root TypeScript source file. This file must be in one of the specified projects. You can add more than one.

-c|--detect-cycles

Runs cycle detection on all the source files reachable from the roots. If it detects a cycle it will print one of the cycles it found and exit with an error status.

Note that it only considers "strong" imports for cycle detection, vs type imports and lazy imports.

-o|--output FILENAME

Outputs a JSON file with the dependency graph.

-v|--verbose

Print messages when it's reading and processing projects.

Example

In our main repository for Glide we have two TypeScript projects - one for the frontend and one for the backend. The frontend one has one root source file and the backend has two - one for the actual backend and one for a CLI. Here's how we run ts-helper to detect cycles in that codebase:

npx "@glideapps/ts-helper" \
    -p ~/Work/glide/functions \
    -r ~/Work/glide/functions/src/cli.ts \
    -r ~/Work/glide/functions/src/index.ts \
    -p ~/Work/glide/app \
    -r ~/Work/glide/app/src/index.tsx \
    -c