[!CAUTION] This repository is archived. As of 2026-01-06 this repo has merged with ember.js and we will no longer be publishing the @glimmer/* packages from this repo separately from ember-source.

[!NOTE] If you have an open PR or issue you'd like considerd you'll unfortunately need to reopen it against ember.js

Glimmer is a flexible, low-level rendering pipeline for building a "live" DOM from Handlebars templates that can subsequently be updated cheaply when data changes.

It is written in TypeScript.

The project is still going through rapid changes at the moment. For the time being, please refer the architecture overview for more information.

Building Glimmer

1. Ensure that Node.js is installed.
2. Run npm install or yarn install to ensure the required dependencies are installed.
3. Run npm run build to build each Glimmer package. The builds will be placed in the dist/ directory.

Glimmer's packages are only built when running npm run build (or ember build --env production). If you run ember build without setting the production environment, dist/ will only contain test assets.

If you want to use the built packages in other projects, you can use npm run yarn:link to execute the yarn link command inside each built package. (You must build the packages first with npm run build).

How to Run Tests

Running all tests

1. Run pnpm test to run all tests.

In a browser

1. Run pnpm start to start the Vite dev server.
2. Open your browser and navigate to the provided URL.
3. Use the QUnit interface to filter and run specific tests.

Node.js tests

1. Run pnpm test:node to run Node.js tests via Turbo.
2. Visit http://localhost:7357/tests/.

TypeScript Notes

"Friend" Properties and Methods

In TypeScript, private and protected refer to the class itself (and its subclasses).

Sometimes, you want to add a property or method that shouldn't be considered part of the external API (for other packages or Ember) but is expected to be used as part of an internal protocol.

In that case, it's ok to mark the property as private or protected and use ['property'] syntax to access the property inside of the same package.

class Layout {
  private template: Template;
}

function compile(layout: Layout, environment: Environment): CompiledBlock {
  return layout['template'].compile(environment);
}

The idea is that the compile function might as well be a private method on the class, but because the function leaks into untyped code, we want to be more careful and avoid exporting it.

Other use-cases might include protocols where a cluster of classes is intended to work together internally, but it's difficult to describe as a single class hierarchy.

This is a semi-blessed workflow according to the TypeScript team, and Visual Studio Code (and tsc) correctly type check uses of indexed properties, and provide autocompletion, etc.

You should not treat use of ['foo'] syntax as license to access private properties outside of the package.

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Cross-browser testing provided by: