DAT-Cross Farm Model
DAT-Cross: Developing Assessments and Tools to Support the Teaching and Learning of Science Crosscutting Concepts
Developed by the Concord Consortium in collaboration with Indiana University (IU) and the Educational Testing Service (ETS).
The farm model is an agent-based model that uses the Populations.js library developed by the Concord Consortium.
The model is available at https://dat-cross.concord.org.
Development
This project was developed using CreateReactApp-TypeScript, which is a fork of CreateReactApp modified to support TypeScript. As of this writing the project has been ejected so it cannot be updated to newer versions of CreateReactApp-TypeScript. The standard README for CreateReactApp, which provides tremendous detail on the infrastructure provided and the configuration options available, is provided below.
Available Scripts
In the project directory, you can run:
npm start
Runs the app in the development mode.
Open http://localhost:3000 to view it in the browser.
The page will reload if you make edits.
You will also see any lint errors in the console.
npm test
Launches the test runner in the interactive watch mode.
See the section about running tests for more information.
npm test:ci
Runs the unit tests non-interactively (ci = continuous integration).
npm run build
Builds the app for production to the build folder.
It correctly bundles React in production mode and optimizes the build for the best performance.
The build is minified and the filenames include the hashes.
Your app is ready to be deployed!
See the section about deployment for more information.
npm run lint
Runs lint on the project sources.
npm run lint:fix
Runs lint on the project sources with the --fix option, which automatically corrects problems (like missing semicolons) that can be fixed programmatically. Any modified source files will need to be committed manually.
npm run lib
Bundles the application together as a library for distribution on npm. This is a two-step process which includes transpiling the Typescript to Javascript, and then copying over any assets.
npm publish
As long as the version is updated in package.json, a new version will be uploaded on npm. You will then be able to import anything exported by libs.ts.
Populations.js Wrapper
The Populations.js library was developed in CoffeeScript and bundled with brunch. Historically, models built using Populations.js were often developed with CoffeeScript and brunch as well, often as part of the Populations Models project. For this project we developed a wrapper for the Populations.js library that allows it to be used from a TypeScript application bundled with WebPack. TypeScript definitions at populations.d.ts provide a typed interface to the capabilities of the Populations.js library.
A pre-built version of the Populations.js library is included in the public folder with the name vendor.js. A local JavaScript file populations.js imports the required symbols from vendor.js using the require_brunch function and then exports them for consumption by the rest of the application. For this to work, the symbol require_brunch is configured as an alias for require at runtime in index.html. (require_brunch is used to prevent WebPack from processing it like regular requires). For unit testing, a hacked version of the Populations.js library is available in the test folder as vendor-test.js in which unused libraries were manually removed (to improve load times) and the require_brunch symbol is explicitly defined as an alias for require. The vendor-test.js library is then loaded into JSDom in setupTests.ts.
Updating to a different version of the Populations.js library would require replacing vendor.js with the new version, and then producing a hacked version of the new version to replace vendor-test.js. Ultimately, once the Populations.js library is updated to support WebPack builds directly, these workarounds should be eliminated.
Asset Attributions
Spider Image from openclipart (Creative Commons Zero 1.0 Public Domain License).
Copy Icon by SmashIcons from FlatIcon (Creative Commons BY 3.0 license).
create-react-app README
The default README provided by CreateReactApp is available at README-CreateReactApp.md. It contains additional information about the infrastructure of the project and the configuration options available.