A repo to play with AtScript.

3 years after

AtScript Playground

This is an empty repo to make it easy to experiment with AtScript.

Initial setup

# Clone the repo...
git clone
cd atscript-playground

# Then, you need to install all the dependencies...
npm install

# If you want to be able to use global commands `karma` and `gulp`...
npm install -g karma-cli gulp

The minimal example

Our example consists of two files:

  • atscript-playground/src/something.ats defines a simple class that returns the sum of two input values
  • atscript-playground/src/main.ats imports that class and prints a message to the console

Running the example in the browser

To run in the browser, you need to first build the project. This creates a build/ directory that contains the transpiled *.js files that are created from your AtScript project.

# Do initial build, start a webserver and re-build on every file change...
gulp build serve watch

Open a browser and look in the console log to see the result.

Running the tests

The tests are in atscript-playground/test/something_spec.ats. Run them using Karma, like so:

karma start

Karma opens a browser window for running tests. To see the actual test output (and errors), look for the log in the terminal window where you issued the karma start command.

What are all the pieces involved?


Transpiles AtScript code into regular ES5 (today's JavaScript) so that it can be run in a current browser.


Traceur is configured to transpile AtScript modules into AMD syntax and we use RequireJS to load the code in the browser.

Assert library

When typeAssertions: true option is used, Traceur generates run-time type assertions such as assert.type(x, Object). The assert library does the actual run-time check. Of course, you can use your own assert library.

The idea with type assertions is that you only use them during the development/testing and when deploying, you use typeAssertions: false.


Test runner that runs the tests in specified browsers, every time that you change a file.


Task runner to make defining and running the tasks simpler.

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