Letify CLI helps Angular developers optimize their templates by scanning your files and detecting multiple async subscriptions to the same stream.

Usage

To get started, install Letify CLI:

npm i -D @jsverse/letify

Then, run the command:

npx letify [analyze|fix] 'a/b.html' 'c/**/*.html' ...

• analyze: Identifies duplicate subscriptions in the specified files and generates a report.
• fix: Identifies duplicate subscriptions and replace duplications with a single @let declaration at the beginning of the template.

CI / Lint-

Letify will return an error exit code if any duplicate subscriptions are detected in the specified files. It can be seamlessly integrated into your lint-staged or CI workflows to prevent duplicate subscriptions from being committed.

Usage notes

• Letify ignores commented code and does not analyze it.
• Keyed reads (data[prop] | async) and function calls with arguments (myMethod(value, ...) | async) are currently not supported.
• You'll need Angular >=18.1 to use the @let syntax, if you are using an older version, run the analyze command and use alternatives to reuse your subscriptions.

Options

• -r, --reporter <type>: Specifies the report format:
  • html (default): Generates an HTML report.
  • list: Outputs a simple list of suggestions.
  • json: Provides a JSON report for programmatic use.
• -o, --open: Automatically opens the HTML report once generated (default true.
• --verify-convention (default: false): Checks that stream names (observables) in the templates follow the convention of ending with a $ sign.
• --variable-suffix (default: value): Adds a suffix to the declared variable in fix mode, mainly to avoid collisions.

Debugging

You can extend the default logs by setting the DEBUG environment variable:

DEBUG=letify:* npx letify ...

Supported namespaces: letify:*|letify:fix.