Package Quirks

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This example shows some of the quirks and miscellaneous things to know about Dimensional and the consequenses of each.

• Create dimensions, instead of using the builtin ones
  • Custom dimensions are not identical to builtin dimensions
• Create the same dimension independently
  • Dimensions initialized independently are also not identical to each other
• Multiplying or dividing dimensions or units by dimensionless or unitless
  • This yields the original dimension or unit
• Creating units with the same prefix independently
  • These units are also not identical to each other, but will have a conversion rate of 1

Installation

Follow these steps to create a new project workspace and install the dimensional dependency to run this example.

# Create and open project folder
mkdir Package_Quirks_demo
cd Package_Quirks_demo
# Initialize project and install dependencies
npm init -y
npm i dimensional@1.3.1
# Create and open source file
touch "Package Quirks.mjs"
open "Package Quirks.mjs"
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Source

Copy and paste this source code into Package Quirks.mjs.

import { Dimension, dimensions, prefixes, Quantity, units } from 'dimensional';

// Define the length dimension
const length_1 = new Dimension('L');

// You can combine dimensions alone
const area = length_1.pow(2);
console.log(area.toString());

// Define the same dimension again
// but it's not the same as the one
// defined previously.
const length_2 = new Dimension('L');
console.log('length_1 == length_2?', length_1.is(length_2));

// It's also not the same as the built-in dimension
console.log('length_1 == length?', length_1.is(dimensions.Length));

// However, multiplying or dividing dimensions by
// "Dimensionless" will not affect the dimension
// > `dimensions.Dimensionless` and `new Dimension()` act the same!
// > Same thing with `units.Unitless` and `new Unit()`
const length_1_x_dimensionless_1 = dimensions.Dimensionless.times(length_1);
const length_2_d_dimensionless_2 = length_2.over(new Dimension());
console.log('length_1 * dimensionless = length_1?', length_1_x_dimensionless_1.is(length_1));
console.log('length_2 / dimensionless = length_2?', length_2_d_dimensionless_2.is(length_2));

// By adding the same prefix to the same unit, but in 2
// distinct instances, the units are no longer identical
const km_1 = units.meter.prefix(prefixes.kilo);
const km_2 = units.meter.prefix(prefixes.kilo);
console.log('km_1 == km_2?', km_1.is(km_2));

// However, their conversion factor is 1
const km_to_km = km_1.to(km_2);
console.log('Conversion factor:', km_to_km);

// That means, quantities using either of
// those units are technically identical
const q1 = new Quantity(5, km_1);
const q2 = q1.as(km_2); // Convert to km_2
console.log(q1.toString(), q2.toString());
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Output

In Package_Quirks_demo/, execute Package Quirks.mjs with NodeJS to generate an output.

node "Package Quirks.mjs"
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You should expect to see an output similar to the one below.

\text{L}^{2}
length_1 == length_2? false
length_1 == length? false
length_1 * dimensionless = length_1? true
length_2 / dimensionless = length_2? true
km_1 == km_2? false
Conversion factor: 1
5 \left[ {\text{k}\text{m}} \right] 5 \left[ {\text{k}\text{m}} \right]
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