first commit

.editorconfig

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+# EditorConfig is awesome: https://editorconfig.org
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 4
+indent_style = space
+insert_final_newline = true

README.md

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+## Advent of Code 2025
+
+At the suggestion of a co-worker, I'm participating in the Advent of Code for 2025, and thiss repo will have my solutions.
+
+While I plan to do some of these in different languages, I'm 2 days in and so far, it's 100% JavaScript (my preferred language over the decade or so, and the one I work in the most).
+
+Each day should have instructions for running it. Fopr the JS stuff, it's node 22 with no special packages.
+

day01/js/day01a.js

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+import { promises as fsPromises } from "fs";
+
+async function asyncReadFile(filename) {
+    try {
+        const contents = await fsPromises.readFile(filename, "utf-8");
+
+        const arr = contents.split(/\r?\n/);
+
+        return arr;
+    } catch (err) {
+        console.error(err);
+    }
+}
+
+// dial 0-99
+
+const DIAL_START = 50;
+
+const Dial = (start = DIAL_START) => {
+    let countZero = 0,
+        current = start;
+    const getCountZero = () => countZero,
+        reset = () => {
+            countZero = 0;
+            current = start;
+        },
+        rotate = (initialVal = "") => {
+            const val = initialVal.trim(),
+                dir = val.length ? val.substring(0, 1).toUpperCase() : "",
+                amount = val.length ? (val.substring(1) * 1) % 100 : 0;
+
+            if (!dir) {
+                console.log(`${val} => invalid value!`);
+            }
+
+            const initial = current;
+
+            if (dir === "R") {
+                current = (current + amount) % 100;
+            } else if (dir === "L") {
+                current =
+                    (current - amount + (current - amount < 0 ? 100 : 0)) % 100;
+            }
+            console.log(
+                `${val} => rotating ${
+                    dir === "R" ? "RIGHT" : "LEFT"
+                } ${amount} from ${initial} to ${current}`
+            );
+
+            if (current === 0) {
+                countZero++;
+                console.log("CountZero!");
+            }
+        };
+
+    return {
+        getCountZero,
+        reset,
+        rotate,
+    };
+};
+
+const dial = Dial();
+
+/*
+// Test Data
+
+const dataToParse = [
+  "L68",
+  "L30",
+  "R48",
+  "L5",
+  "R60",
+  "L55",
+  "L1",
+  "L99",
+  "R14",
+  "L82",
+];
+*/
+
+const dataToParse = await asyncReadFile("../input.txt");
+
+dataToParse.forEach((val) => {
+    if (val.trim()) dial.rotate(val);
+});
+
+console.log(`Final countZero is ${dial.getCountZero()}`);

day01/js/day01b.js

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+import { readFileSync, promises as fsPromises } from "fs";
+
+async function asyncReadFile(filename) {
+    try {
+        const contents = await fsPromises.readFile(filename, "utf-8");
+
+        const arr = contents.split(/\r?\n/);
+
+        // console.log(arr); // 👉️ ['One', 'Two', 'Three', 'Four']
+
+        return arr;
+    } catch (err) {
+        console.error(err);
+    }
+}
+
+// dial 0-99
+
+const DIAL_START = 50;
+
+const Dial = (start = DIAL_START) => {
+    let countZero = 0,
+        current = start;
+    const getCountZero = () => countZero,
+        reset = () => {
+            countZero = 0;
+            current = start;
+        },
+        rotate = (initialVal = "") => {
+            const val = initialVal.trim(),
+                dir = val.length ? val.substring(0, 1).toUpperCase() : "",
+                originalAmount = val.length ? val.substring(1) * 1 : 0,
+                amount = originalAmount % 100,
+                hundreds = Math.floor(originalAmount / 100);
+
+            if (!dir) {
+                console.log(`${val} => invalid value!`);
+            }
+
+            const initial = current;
+
+            if (hundreds) {
+                countZero += hundreds;
+                console.log(`${val} => has hundreds: ${hundreds} x CountZero!`);
+            }
+
+            if (dir === "R") {
+                if (current + amount > 100) {
+                    countZero++;
+                    console.log(`${val} => passing 0: CountZero!`);
+                }
+                current = (current + amount) % 100;
+            } else if (dir === "L") {
+                if (current && current - amount < 0) {
+                    countZero++;
+                    console.log(`${val} => passing 0: CountZero!`);
+                }
+                current = (100 + current - amount) % 100;
+            }
+            console.log(
+                `${val} => rotating ${
+                    dir === "R" ? "RIGHT" : "LEFT"
+                } ${amount} from ${initial} to ${current}`
+            );
+
+            if (current === 0) {
+                countZero++;
+                console.log("CountZero!");
+            }
+        };
+
+    return {
+        getCountZero,
+        reset,
+        rotate,
+    };
+};
+
+const dial = Dial();
+
+// Test Data
+/*
+const dataToParse = [
+  "L68",
+  "L30",
+  "R48",
+  "L5",
+  "R60",
+  "L55",
+  "L1",
+  "L99",
+  "R14",
+  "L82",
+];
+*/
+
+const dataToParse = await asyncReadFile("../input.txt");
+
+dataToParse.forEach((val) => {
+    if (val.trim()) dial.rotate(val);
+});
+
+console.log(`Final countZero is ${dial.getCountZero()}`);

day01/notes.md

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+## Day 1: Secret Entrance
+
+This was fun, took about 90 minutes to get first two solutions (in JS).
+
+### JS Solutions
+
+```
+cd js
+node day01a.js
+node day01b.js
+```

day02/input.txt

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+3335355312-3335478020,62597156-62638027,94888325-95016472,4653-6357,54-79,1-19,314-423,472-650,217886-298699,58843645-58909745,2799-3721,150748-178674,9084373-9176707,1744-2691,17039821-17193560,2140045-2264792,743-1030,6666577818-6666739950,22946-32222,58933-81008,714665437-714803123,9972438-10023331,120068-142180,101-120,726684-913526,7575737649-7575766026,8200-11903,81-96,540949-687222,35704-54213,991404-1009392,335082-425865,196-268,3278941-3383621,915593-991111,32-47,431725-452205

day02/js/day02a.js

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+import { promises as fsp } from "node:fs";
+
+async function asyncReadFile(filename) {
+    try {
+        const contents = await fsp.readFile(filename, "utf-8");
+
+        return contents.trim();
+    } catch (err) {
+        console.error(err);
+    }
+}
+
+/*
+const dataToParse =
+    "11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124";
+*/
+
+const dataToParse = await asyncReadFile("../input.txt");
+
+const isDuplicate = (val = "") => {
+    const strVal = `${val}`,
+        strLen = strVal.length;
+    if (!strLen || strLen % 2 === 1) return false;
+
+    return strVal.substring(0, strLen / 2) === strVal.substring(strLen / 2);
+};
+
+const ranges = dataToParse.split(",");
+let total = 0;
+
+ranges.forEach((range) => {
+    console.log(`> running range ${range}`);
+    const [start, end] = range.split("-"),
+        last = end * 1;
+    let curr = start * 1;
+    while (curr <= last) {
+        if (isDuplicate(curr)) {
+            total += curr;
+            console.log(`>> found duplicate: ${curr} / ${total}`);
+        }
+        curr++;
+    }
+});
+
+console.log(`> FINAL: ${total}`);

day02/js/day02b.js

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+import { promises as fsp } from "node:fs";
+
+async function asyncReadFile(filename) {
+    try {
+        const contents = await fsp.readFile(filename, "utf-8");
+
+        return contents.trim();
+    } catch (err) {
+        console.error(err);
+    }
+}
+
+/*
+const dataToParse =
+    "11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124";
+*/
+
+const dataToParse = await asyncReadFile("../input.txt");
+
+const isDuplicateOld = (val = "") => {
+    const strVal = `${val}`,
+        strLen = strVal.length;
+    if (!strLen || strLen % 2 === 1) return false;
+
+    return strVal.substring(0, strLen / 2) === strVal.substring(strLen / 2);
+};
+
+const duplicateRE = /^(\d+)\1+$/;
+const isDuplicate = (val = "") => {
+    // new process - runa  regex that looks for repeats from start to end
+    const strVal = `${val}`,
+        strLen = strVal.length;
+    if (!strLen) return false;
+
+    const matches = strVal.match(duplicateRE);
+
+    if (matches === null) return false;
+
+    return matches.length >= 1 && matches[0] === strVal;
+};
+
+const ranges = dataToParse.split(",");
+let total = 0;
+
+ranges.forEach((range) => {
+    console.log(`> running range ${range}`);
+    const [start, end] = range.split("-"),
+        last = end * 1;
+    let curr = start * 1;
+    while (curr <= last) {
+        if (isDuplicate(curr)) {
+            total += curr;
+            console.log(`>> found duplicate: ${curr} / ${total}`);
+        }
+        curr++;
+    }
+});
+
+console.log(`> FINAL: ${total}`);

day02/notes.md

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+## Day 2: Gift Shop
+
+This got a bit frustrating with the regex in the second part.
+
+It only took about 30 minutes to solve first part, but my answer involved literally splitting strings, so it didn't work for arbitrary matches and had to be replaced by a regex solution. After struggling with the regex for another 30 minutes, I put it away until the next day, when a 5-minute web search lead me to the fix for my bad regex.
+
+### JS Solutions
+
+```
+cd js
+node day01a.js
+node day01b.js
+```