feat: add force units.

apps/docs/src/content/docs/conversions/force.mdx

@@ -0,0 +1,38 @@
+---
+title: "Force"
+template: doc
+---
+
+The **force** category supports conversions between Newton, Dyne, Poundal, Pound-Force, and Kilogram-Force.
+
+## Supported Units
+
+- Newton `N`
+- Dyne `dyn`
+- Poundal `pdl`
+- Pound-Force `lbf`
+- Kilogram-Force `kgf`
+
+## Quick Example
+
+```ts
+import { Conversion } from "@devhaven/unit-conversion";
+
+const convert = new Conversion();
+
+convert.value(10).from("newton").to("dyne");
+convert.value(5000).from("dyne").to("newton");
+```
+
+## Common Conversions
+### Newton ↔ Kilogram-Force
+```ts
+convert.value(1).from("newton").to("kilogram-force");
+convert.value(1).from("kilogram-force").to("newton");
+```
+
+### Newton ↔ Pound-Force
+```ts
+convert.value(1).from("newton").to("pound-force");
+convert.value(1).from("pound-force").to("newton");
+```

packages/unit-conversion/src/constants/labels.ts

@@ -111,14 +111,21 @@ export const LABELS = {
   fahrenheit: "°F",
   rankine: "°R",
   delisle: "°De",
-  newton: "°N",
+  "newton-degree": "°N",
   réaumur: "°Ré",
   rømer: "°Rø",
 
   // luminous intensity
   candela: "cd",
   stilb: "sb",
 
+  // Force
+  newton: "N",
+  dyne: "dyn",
+  poundal: "pdl",
+  "pound-force": "lbf",
+  "kilogram-force": "kgf",
+
   // pressure
   pascal: "Pa",
   kilopascal: "kPa",

packages/unit-conversion/src/constants/units.ts

@@ -27,7 +27,7 @@ export type EnergyUnits =
   | "kilowatt-hour"
   | "electron-volt";
 export type AngleUnits = "radian" | "degree" | "gradian" | "arcminute" | "arcsecond";
-
+export type ForceUnits = "newton" | "dyne" | "pound-force" | "kilogram-force" | "poundal";
 export type AllUnits =
   | TemperatureUnits
   | LengthUnits
@@ -37,7 +37,8 @@ export type AllUnits =
   | NumberUnits
   | PressureUnits
   | EnergyUnits
-  | AngleUnits;
+  | AngleUnits
+  | ForceUnits;
 
 export type UnitCategory<T extends AllUnits> = T extends TemperatureUnits
   ? TemperatureUnits
@@ -51,13 +52,15 @@ export type UnitCategory<T extends AllUnits> = T extends TemperatureUnits
           ? TimeUnits
           : T extends NumberUnits
             ? NumberUnits
-            : T extends PressureUnits
-              ? PressureUnits
-              : T extends EnergyUnits
-                ? EnergyUnits
-                : T extends AngleUnits
-                  ? AngleUnits
-                  : never;
+            : T extends ForceUnits
+              ? ForceUnits
+              : T extends PressureUnits
+                ? PressureUnits
+                : T extends EnergyUnits
+                  ? EnergyUnits
+                  : T extends AngleUnits
+                    ? AngleUnits
+                    : never;
 
 export type ALL_UNIT_CATEGORIES = {
   temperature: TemperatureUnits[];
@@ -69,6 +72,7 @@ export type ALL_UNIT_CATEGORIES = {
   pressure: PressureUnits[];
   energy: EnergyUnits[];
   angle: AngleUnits[];
+  force: ForceUnits[];
 };
 
 /**
@@ -118,6 +122,7 @@ export const UNITS: ALL_UNIT_CATEGORIES = {
     "electron-volt",
   ],
   angle: ["degree", "radian", "gradian", "arcminute", "arcsecond"],
+  force: ["newton", "dyne", "pound-force", "kilogram-force", "poundal"],
 };
 
 export const NO_UNITS_CATEGORIES = ["number"];

packages/unit-conversion/src/index.ts

@@ -3,6 +3,7 @@ export { LABELS } from "./constants/labels";
 export type {
   ALL_UNIT_CATEGORIES,
   AllUnits,
+  ForceUnits,
   LengthUnits,
   NumberUnits,
   TemperatureUnits,

packages/unit-conversion/src/utils/common.ts

@@ -30,6 +30,7 @@ export function getUnitCategory(unit: AllUnits): keyof typeof CONVERSION_FACTORS
   if (isUnitInCategory(unit, "pressure")) return "pressure";
   if (isUnitInCategory(unit, "energy")) return "energy";
   if (isUnitInCategory(unit, "angle")) return "angle";
+  if (isUnitInCategory(unit, "force")) return "force";
 
   throw new Error(`Unknown unit: ${unit}`);
 }

packages/unit-conversion/src/utils/conversion-factors.ts

@@ -51,6 +51,7 @@ interface ConversionFactorGroups {
  * @property {Object} weight - Weight conversions with gram as base unit
  * @property {Object} volume - Volume conversions with liter as base unit
  * @property {Object} time - Time conversions with second as base unit
+ * @property {Object} force - Force conversions with Newton as base unit
  */
 export const CONVERSION_FACTORS: ConversionFactorGroups = {
   // Temperature (base: Kelvin)
@@ -387,4 +388,29 @@ export const CONVERSION_FACTORS: ConversionFactorGroups = {
     },
   },
   // Angle (base: radian)
+
+  // Force (base: newton)
+  force: {
+    newton: {
+      isBaseUnit: true,
+      toBase: (v: number) => v,
+      fromBase: (v: number) => v,
+    },
+    dyne: {
+      toBase: (v: number) => v * 1e-5,
+      fromBase: (v: number) => v / 1e-5,
+    },
+    poundal: {
+      toBase: (v: number) => v * 0.138255,
+      fromBase: (v: number) => v / 0.138255,
+    },
+    "pound-force": {
+      toBase: (v: number) => v * 4.44822,
+      fromBase: (v: number) => v / 4.44822,
+    },
+    "kilogram-force": {
+      toBase: (v: number) => v / 0.1019716213,
+      fromBase: (v: number) => v * 0.1019716213,
+    },
+  },
 };

packages/unit-conversion/tests/conversion.spec.ts

@@ -1,6 +1,5 @@
 import { describe, expect, test } from "vitest";
-import type { AllUnits } from "../src";
-import { Conversion } from "../src/main";
+import { type AllUnits, Conversion } from "../src";
 
 type TestValues = {
   value: number;
@@ -474,3 +473,35 @@ describe("Test energy conversions", () => {
     });
   });
 });
+
+describe("Test force conversions", () => {
+  const forceTests: Array<TestValues> = [
+    { value: 1, from: "newton", to: "pound-force", expected: "0.2248", unit: "lbf" },
+    { value: 1, from: "newton", to: "kilogram-force", expected: "0.1019", unit: "kgf" },
+    { value: 1, from: "newton", to: "dyne", expected: "100000", unit: "dyn" },
+    { value: 1, from: "newton", to: "poundal", expected: "7.2330", unit: "pdl" },
+    { value: 1, from: "dyne", to: "newton", expected: "0.00001", unit: "N" },
+    { value: 1, from: "dyne", to: "pound-force", expected: "0", unit: "lbf" },
+    { value: 1, from: "dyne", to: "kilogram-force", expected: "0", unit: "kgf" },
+    { value: 1, from: "dyne", to: "poundal", expected: "0.00001", unit: "pdl" },
+    { value: 1, from: "poundal", to: "newton", expected: "0.1383", unit: "N" },
+    { value: 1, from: "poundal", to: "dyne", expected: "13825.5", unit: "dyn" },
+    { value: 1, from: "poundal", to: "pound-force", expected: "0.03108", unit: "lbf" },
+    { value: 1, from: "poundal", to: "kilogram-force", expected: "0.01409", unit: "kgf" },
+    { value: 1, from: "pound-force", to: "newton", expected: "4.4482", unit: "N" },
+    { value: 1, from: "pound-force", to: "kilogram-force", expected: "0.4536", unit: "kgf" },
+    { value: 1, from: "kilogram-force", to: "newton", expected: "9.8066", unit: "N" },
+    { value: 1, from: "kilogram-force", to: "pound-force", expected: "2.2046", unit: "lbf" },
+  ];
+  const convert = new Conversion({
+    decimals: 4,
+  });
+
+  forceTests.forEach(({ value, from, to, expected, unit }) => {
+    test(`Converts ${value} ${from} to ${to}`, () => {
+      const result = convert.value(value).from(from).to(to);
+      expect(isApproximatelyEqual(+result.value, +expected)).toBe(true);
+      expect(result.unit).toBe(unit);
+    });
+  });
+});