Metrick

0.2.0 verified Sat Apr 25 auth: no javascript

Metrick is a Babel-powered unit conversion library (v0.2.0) that leverages the ES7 function bind syntax (::) for human-readable unit expressions. It supports duration (milliseconds, seconds, minutes, hours, years) and data (bits, bytes, kilobytes, megabytes, gigabytes, etc.) conversions with explicit (unit::unit.in(target)) and implicit (number::unit) syntax. The library requires the Babel plugin transform-function-bind and is designed for Node.js and browser environments. Alternatives like js-quantities or convert-units offer more units or simpler syntax but lack the syntactic sugar of the bind operator. Release cadence is low; last release was 2017.

Common errors

error SyntaxError: Unexpected token : ↓

cause Using :: bind syntax without Babel plugin or in unsupported environment.

fix

Install and configure Babel with @babel/plugin-proposal-function-bind.

error Module not found: Can't resolve 'metrick' ↓

cause Importing from 'metrick' when the package does not export units from the main entry.

fix

Import from subpaths like 'metrick/duration' for unit functions.

error TypeError: seconds.in is not a function ↓

cause Using .in on a number instead of a Unit object. The correct syntax is number::unit.in(targetUnit).

fix

Use the :: operator: 30::seconds.in(milliseconds) instead of 30.seconds.in(milliseconds).

Warnings

deprecated Babel plugin transform-function-bind is deprecated in Babel 7+; use @babel/plugin-proposal-function-bind instead. ↓

fix Replace 'transform-function-bind' with '@babel/plugin-proposal-function-bind' in .babelrc.

breaking The function bind syntax (::) is not supported in Node.js or browsers without Babel; code will fail to parse. ↓

fix Always transpile code with Babel and the function bind plugin before running.

gotcha Importing from 'metrick' (index) only exports Unit class; unit modules are at subpaths like 'metrick/duration'. ↓

fix Use correct subpath imports: import { seconds } from 'metrick/duration'.

gotcha Unit conversions use SI prefixes (e.g., kilograms = 1000 grams), not binary prefixes (e.g., kibibytes). ↓

fix Use 'metrick/data' for data units; note that megabyte = 1e6 bytes, not 2^20.

Install

npm install metrick

yarn add metrick

pnpm add metrick

Imports

seconds
wrong
```
import { seconds } from 'metrick'
```
correct
```
import { seconds } from 'metrick/duration'
```
Units are exported from subpath modules like 'metrick/duration' or 'metrick/data'; 'metrick' only exports the Unit class.
Unit
wrong
```
import { Unit } from 'metrick'
```
correct
```
import Unit from 'metrick/unit'
```
Unit is the default export from 'metrick/unit'; named import from 'metrick' does not exist.
megabytes
wrong
```
const { megabytes } = require('metrick');
```
correct
```
import { megabytes } from 'metrick/data'
```
CommonJS require is not recommended; library is primarily designed for ESM with Babel.

Quickstart

Demonstrates importing units, explicit conversion with ::x.in(y), implicit conversion to base unit, and creating custom units.

// Ensure babel-plugin-transform-function-bind is installed and configured in .babelrc
import { seconds, minutes, milliseconds } from 'metrick/duration';
import { megabytes, gigabytes } from 'metrick/data';

// Explicit conversion
const msInMinute = 1::minutes.in(milliseconds);
console.log(`1 minute = ${msInMinute} ms`); // 60000

// Implicit conversion (defaults to SI base unit)
const bitsInMegabyte = 1::megabytes;
console.log(`1 megabyte = ${bitsInMegabyte} bits`); // 8000000

// Chain conversions
const gbInMb = 1::gigabytes.in(megabytes);
console.log(`1 GB = ${gbInMb} MB`); // 1000

// Create custom units
import Unit from 'metrick/unit';
const lux = new Unit();
const lumen = new Unit(10.7639::lux);
const brightness = 100::lumen.in(lux);
console.log(`100 lumens = ${brightness} lux`); // 1076.39