Skyalert Typescript Scaffolding

Clone this project to jump-start a TS project. It contains tools and configurations for TDD best practices, so that your environment can give you instant feedback on your work.

Included in the box

• typescript: used to transpile your code into JS.
• ts-node: typeScript execution engine and REPL for Node.js.
• jest: unit testing
• eslint: code style enforcement
• prettier: code formatting enforcement
• typedoc: automatic doc generation
• husky: git hooks

Available scripts

• yarn start - run your application and watch for changes
• test - run all tests
• test-watch - jest interactive terminal
• lint - check for style errors and warnings
• clean - delete ./dist folder
• build - transpile into ./dist folder
• build-watch - watch for changes and transpile into ./dist folder
• build-all - check for style errors, delete ./dist and build

Installation

1. Download/clone this repo
2. yarn
3. yarn prepare
4. Go to package.json and fill out the name, description and author
5. git init
6. git add .
7. git commit -m "Scaffolding complete"
8. Add a remote repository

How to use

This is a walkthrough of the available tools.

test-watch

1. Open a terminal window and run yarn test-watch.
2. All green? Good.
3. Open src/index.test.ts
4. At the end, write the following test:

describe('When multiplying two numbers', () => {
  it('should return the product', () => {
    expect(multiply(3, 5)).toBe(15);
  });
});

5. You can immediately see that multiply(3,5) is hightlighted as an error.
6. Save the file anyway.
7. Now your test fail with:

src/index.test.ts:11:12 - error TS2304: Cannot find name 'multiply'.

8. Now open src/index.ts and write an implementation:

export const multiply = (a: number, b: number): number => a * b;

9. Import your new function into the .test file

- import { sum } from './index';
+ import { sum, multiply } from './index';

10. Save both files and watch the test pass.

eslint + prettier

11. Run yarn lint in your terminal. If nothing happens, you are good.
12. Run

echo "crappyCode(a, b) => a /b" >> src/index.ts

13. Run yarn lint. You'll see at least an error. (also in the test-watch terminal)
14. Fix it like so:

export const divide = (a: any, b: any) => a / b;

15. Run yarn lint again. You'll see it complains with a warning. Let's fix it:

export const divide = (a: number, b: number) => a / b;

husky

16. Run

echo "export const subtract = (a: number, b: number) => { return a - b };
" >> src/index.ts

17. Try to commit this to the repo. If you followed the "Installation" section, it should fail.

18. Replace with:

export const subtract = (a: number, b: number) => a - b;

19. Commit (if you want, if not just run yarn lint). It should not produce an error.

start

20. Run yarn start
21. Write:

const a = 6;
const b = 3;

console.log(sum(a, b));

22. Save and watch the terminal output. It should print 9
23. Make a small change:

-console.log(sum(a, b));
+console.log(multiply(a, b));

24. Save and watch the terminal output. It should print 18

docs

25. Run yarn docs
26. Open docs/index.html in a web browser. Explore your new documentation.
27. In src/index.ts add:

/**
 * Calculates the square root of a number.
 *
 * @param x the number to calculate the root of.
 * @returns the square root if `x` is non-negative or `NaN` if `x` is negative.
 */
export const sqrt = (x: number): number => Math.sqrt(x);

28. Run yarn docs and reload your web browser. Explore the new function.

develop

29. Just replace index.ts and index.test.ts and do as you please.