linesman-demo

The project demonstrates how to use linesman to organize the snippets of verifying JS tricks and pitfalls.

The linesman library

See linesman.

Usage

First, run npm install to install the dependencies.

Then, you may run the whole project, or run the individual script one by one:

npm run dev   # run the whole project

node math.js  # run an individual script
npm run math  # the same with previous line since it's written in `package.json`

Or, you may run the project in a watch mode:

npm run watch

Note: if you see no errors, then it means no error. (No news is good news.)

Example

The following is the content of the math.js file:

const {yes, not} = require('linesman');

// ---- NaN
// you CAN NOT compare `NaN` with itself.
not.ok(NaN == NaN);
not.ok(NaN === NaN);
not.ok(NaN > NaN);
not.ok(NaN < NaN);
yes.ok(isNaN(NaN)); // use `isNaN()` to check an value is `NaN` or not

// the cases result in `NaN`
yes.ok(isNaN('Hello' - 1));
yes.ok(isNaN('Hello' - 'H'));
yes.ok(isNaN(undefined + undefined));
yes.ok(isNaN(undefined - undefined));
yes.ok(isNaN(undefined + 1));

// ---- Infinity
yes.se(Infinity, Infinity);
yes.se(Infinity, Infinity - 1); // subtract one year from `forever` is still `forever`

yes.se(1 / 0, Infinity);
yes.se((-1) / 0, -Infinity);
yes.se(1 / null, Infinity);
yes.ok(isNaN(1 / undefined));

yes.ok(isNaN(Infinity + (-Infinity))); // you cannot sum them up.

License

MIT