amounts v0.5.0

Amounts

Represent amounts of stuff with units and conversions. Supports lenient parsing of amounts, normalization and basic formatting.

const { length, duration } = require('amounts');

// Supports parsing from strings:
const value = length('30 m');
// Convert into another unit (returns a number)
console.log(length.as('ft'));
console.log(length.feet);

// Parse durations
console.log(duration('20 m, 4 s'));

// Supports precision on the numbers
length('2.8 cm')
length('2e10 m')

Amounts tries to be friendly with handling input, supporting variations of units, such as both short and long names, with longer unit names being case insensitive.

These will all parse to the same unit and value:

mass('750 ug');
mass('750 micrograms');
mass('750 micro gram');
mass('750 MikroGram')

But this will not work:

mass('750 uG');

Or fetch units from factories and use convert:

// To convert to mmHg
pressure.unit('mmHg').convert('200.12 kPa');
// Or back to kPa
pressure.unit('kPa').convert(1501.023, 'mmHg');

API

All amounts that can be represented share a common API. Factories support:

• factory(string)

  Parse the given string into an amount.

• factory(value, unit)

  Create an amount with the given value and unit.

• factory(value)

  Create an amount with the given value and the default unit.

• factory.unit(unit)

  Get a unit that can be used for conversions for this factory.

Instances have the following API:

• amount.value: Number

  Get the value of the amount.

• amount.unit: String

  Get the unit of the amount.

• amount.as(unit): Number

  Convert the amount to the given unit and return the result as a number.

• amount.to(unit): Amount

  Convert the amount into another unit and return an object with the value.

Every amount also exposes getters for the most commonly used units:

length('20 cm').meters
length('19 ft').cm

volume(1, 'l').oz

Generic amounts

The generic amount does not have any units, but supports SI-prefixes.

const { generic } = require('amounts');

// Without any unit, returns an amount with value 20
console.log(generic(20));

// With a generic SI-unit, returns an amount with value 20000
console.log(generic('20k'));

// Full length names are supported
console.log(generic('20 micro'))

SI-prefixes

Units in the SI system can be combined with SI-prefixes to create a new unit. SI-prefixes are supported both by their short names and their long names. Examples: cm, milliliters, hPa, MW, kilowatt

Angle

const { angle } = require('amounts');

console.log(angle(2, 'rad'));
console.log(angle('5 degrees').as('radians'));

Area

const { area } = require('amounts');

console.log(area(2, 'm^2'));
console.log(area('10 sq ft').as('m2'));

Duration

Durations represent a number of milliseconds something takes. Multiple units can be combined into a value.

const { duration } = require('amounts');

console.log(duration(2000)); // Defaults to milliseconds
console.log(duration('1d'));
console.log(duration('2h 10m'));
console.log(duration('2 days, 5 hours'));

Energy

const { energy } = require('amounts');

console.log(energy(10)); // Joules
console.log(energy('3.5 kJ').kWh);

Illuminance

const { illuminance } = require('amounts');

console.log(illuminance(2, 'lx'));
console.log(angle('8000 lux'));

Length

const { length } = require('amounts');

console.log(length(2)); // Meters
console.log(length('5 ft').as('micrometer'));
console.log(length('2 ft ').cm);

Mass

const { mass } = require('amounts');

console.log(mass(210)); // Grams
console.log(mass('78 kg').lbs);
console.log(mass('2 stone').kg)

Power

const { power } = require('amounts');

console.log(power(500)); // Watts
console.log(power('6000 kW').mW);
console.log(power('6 hp').as('microwatts'));

Pressure

const { pressure } = require('amounts');

console.log(pressure(500)); // Pascal
console.log(power('700 hPa').atm);
console.log(power('7 bar').kPa);

Sound Pressure Level

const { soundPressureLevel } = require('amounts');

console.log(soundPressureLevel(30)); // db
console.log(soundPressureLevel(30, 'dB')); // db

Speed

const { speed } = require('amounts');

console.log(speed(500)); // m/s
console.log(speed('5 km/s').kph);
console.log(speed('10 mph').mps);

Temperature

const { temperature } = require('amounts');

console.log(temperature(22)); // Celsius
console.log(temperature('200 K').celsius);
console.log(temperature(80, 'f').kelvin);

Voltage

const { voltage } = require('amounts');

console.log(voltage(22)); // Volts
console.log(voltage('200 V').volts);

Volume

const { volume } = require('amounts');

console.log(volume(2)); // Liters
console.log(volume(2, 'quarts').dl);
console.log(volume('20 ml').tbsp);