taxer v0.1.1

taxer

universal tax calculator javascript library to calculate all kinds of taxes through out the world.

Library Architecture

It's designed with plugin mechanism and minimalist in mind. By default:

const taxer = new Taxer();
taxer.use(new CustomCalctor());
const taxInfo = taxer.calc(countryCode, income, options);

in which:

CustomCalctor should be a class implements Calctor interface which has:

• isMatched(countryCode, taxableIncome, options) method: to be hooked up if it is the first to return true.
• calc(taxableIncome, options) method: the taxInfo is calculated and returned.

If no matched calculator, an error will be thrown.

For example:

export class VnCalctor {
    constructor() {
    }

    calc(taxableIncome, options={}) {
        return {
            taxableIncome: taxableIncome
        }
    }

    isMatched(countryCode, income, options) {
        if (typeof countryCode === 'string') {
            countryCode = countryCode.toLowerCase();
        }
        return ['vn', 'vnm', 704, 'vietnam', 'viet nam'].indexOf(countryCode) > -1;
    }
}

That's how the library architecture works.

How to use

1. Configure

   1.1. From the default taxer with built-in tax calculators:

   const taxer = defaultTaxer();
   // add more custom calculator
   taxer.use(new CustomCalctor(options));

   1.2. From scratch

   const taxer = new Taxer();
   taxer.use(VnCalctor());
   taxer.use(UsaCalctor());
   taxer.use(SgCalctor());
   taxer.use(CustomCalctor(options));

2. Use

const taxInfo = taxer.calc(countryCode, income, options);
console.log(taxInfo);

How to develop

This is the minimalist plugin architecture inspired by express.js and koa.js a lot. Let's keep it as minimal and lightweight as possible.

Clone this repository and:

$ npm install
$ npm run test

Or with Docker:

$ docker-compose up

How to contribute

By writing custom tax plugins to create a good solid universal tax system throughout the world.

Follow Teracy workflow: http://dev.teracy.org/docs/workflow.html

References

These are related similar projects we should take a look:

• https://github.com/rkh/income-tax

• https://www.npmjs.com/package/uk-income-tax

License

MIT license. See LICENSE file.