Move common functions into separate file

12/12_1.js

@@ -1,6 +1,5 @@
-const util = require("util");
-const Vector3 = require("./Vector3");
 const Moon = require("./Moon");
+const { step, parseInput } = require("./common");
 
 const input = parseInput([
     "<x=14, y=15, z=-2>",
@@ -24,50 +23,6 @@ for (let i = 0; i < STEPS; i++) {
 
 console.log(`Total energy in system is: ${calculateTotalEnergy(input)}`);
 
-/**
- * Calculate one step of time
- *
- * @param {Moon[]} moons A list of moons
- * @returns {void}
- */
-function step(moons) {
-    for (let i = 0; i < moons.length - 1; i++) {
-        for (let j = i + 1; j < moons.length; j++) {
-            // Calculate Moon B's gravity influence on Moon A
-            const firstGravity = calculateGravity(moons[i], moons[j]);
-            // Invert the signage to represent Moon A's influence on Moon B
-            const secondGravity = firstGravity.negate();
-
-            moons[i].velocity.add(firstGravity);
-            moons[j].velocity.add(secondGravity);
-        }
-    }
-
-    moons.forEach((moon) => { moon.position.add(moon.velocity); });
-}
-
-/**
- * Find the gravitational influence two moons have on each other
- *
- * @param {Moon} moonA The first moon to consider
- * @param {Moon} moonB The second moon to consider
- *
- * @returns {Vector3} The gravitational influence of Moon B on Moon A
- */
-function calculateGravity(moonA, moonB) {
-    // The gravitational pull on Moon A caused by Moon B
-    const gravityDifference = new Vector3(
-        // eslint-disable-next-line no-nested-ternary
-        moonB.position.x > moonA.position.x ? 1 : (moonB.position.x < moonA.position.x ? -1 : 0),
-        // eslint-disable-next-line no-nested-ternary
-        moonB.position.y > moonA.position.y ? 1 : (moonB.position.y < moonA.position.y ? -1 : 0),
-        // eslint-disable-next-line no-nested-ternary
-        moonB.position.z > moonA.position.z ? 1 : (moonB.position.z < moonA.position.z ? -1 : 0),
-    );
-
-    return gravityDifference;
-}
-
 /**
  * Calculate the total energy in the system
  *
@@ -89,21 +44,4 @@ function calculateTotalEnergy(moons) {
     return energy;
 }
 
-/**
- * @param {string[]} inputs The day's input
- * @returns {Moon[]} An array of Moon objects
- */
-function parseInput(inputs) {
-    const moons = [];
-    const parseRegex = new RegExp(/x=(-?\d+), y=(-?\d+), z=(-?\d+)/);
-
-    for (const position of inputs) {
-        // eslint-disable-next-line no-shadow-restricted-names
-        const [undefined, x, y, z] = position.match(parseRegex);
-        moons.push(new Moon(new Vector3(parseInt(x, 10), parseInt(y, 10), parseInt(z, 10))));
-    }
-
-    return moons;
-}
-
 // console.log(util.inspect(parseInput(input)));

12/common.js

@@ -0,0 +1,68 @@
+const Moon = require("./Moon");
+const Vector3 = require("./Vector3");
+
+/**
+ * @param {string[]} inputs The day's input
+ * @returns {Moon[]} An array of Moon objects
+ */
+function parseInput(inputs) {
+    const moons = [];
+    const parseRegex = new RegExp(/x=(-?\d+), y=(-?\d+), z=(-?\d+)/);
+
+    for (const position of inputs) {
+        // eslint-disable-next-line no-shadow-restricted-names
+        const [undefined, x, y, z] = position.match(parseRegex);
+        moons.push(new Moon(new Vector3(parseInt(x, 10), parseInt(y, 10), parseInt(z, 10))));
+    }
+
+    return moons;
+}
+
+/**
+ * Calculate one step of time
+ *
+ * @param {Moon[]} moons A list of moons
+ * @returns {void}
+ */
+function step(moons) {
+    for (let i = 0; i < moons.length - 1; i++) {
+        for (let j = i + 1; j < moons.length; j++) {
+            // Calculate Moon B's gravity influence on Moon A
+            const firstGravity = calculateGravity(moons[i], moons[j]);
+            // Invert the signage to represent Moon A's influence on Moon B
+            const secondGravity = firstGravity.negate();
+
+            moons[i].velocity.add(firstGravity);
+            moons[j].velocity.add(secondGravity);
+        }
+    }
+
+    moons.forEach((moon) => { moon.position.add(moon.velocity); });
+}
+
+/**
+ * Find the gravitational influence two moons have on each other
+ *
+ * @param {Moon} moonA The first moon to consider
+ * @param {Moon} moonB The second moon to consider
+ *
+ * @returns {Vector3} The gravitational influence of Moon B on Moon A
+ */
+function calculateGravity(moonA, moonB) {
+    // The gravitational pull on Moon A caused by Moon B
+    const gravityDifference = new Vector3(
+        // eslint-disable-next-line no-nested-ternary
+        moonB.position.x > moonA.position.x ? 1 : (moonB.position.x < moonA.position.x ? -1 : 0),
+        // eslint-disable-next-line no-nested-ternary
+        moonB.position.y > moonA.position.y ? 1 : (moonB.position.y < moonA.position.y ? -1 : 0),
+        // eslint-disable-next-line no-nested-ternary
+        moonB.position.z > moonA.position.z ? 1 : (moonB.position.z < moonA.position.z ? -1 : 0),
+    );
+
+    return gravityDifference;
+}
+
+module.exports = {
+    parseInput,
+    step,
+};