diff --git a/04/code.js b/04/code.js
new file mode 100644
index 0000000..13ce4e4
--- /dev/null
+++ b/04/code.js
@@ -0,0 +1,143 @@
+import { readFileSync } from 'node:fs';
+
+let sampleMode = false;
+let usedArray = [];
+
+const sampleArray = readFileSync('sample.txt').toString().split("\n");
+const inputArray = readFileSync('input.txt').toString().split("\n");
+
+if (sampleMode) {
+  usedArray = [].concat(sampleArray);
+} else {
+  usedArray = [].concat(inputArray);
+}
+
+// Part One
+
+console.time("part1");
+let sum = 0;
+
+for (let i = 0; i < usedArray.length; i++) {
+  let row = usedArray[i];
+  for (let j = 0; j < row.length; j++) {
+    let cell = row[j];
+    if (cell === '@') {
+      let openSides = 0;
+      const left = j > 0 ? row[j - 1] : '.';
+      const right = j < row.length - 1 ? row[j + 1] : '.';
+      const up = i > 0 ? usedArray[i - 1][j] : '.';
+      const down = i < usedArray.length - 1 ? usedArray[i + 1][j] : '.';
+      const upperLeft = i > 0 && j > 0 ? usedArray[i - 1][j - 1] : '.';
+      const upperRight = i > 0 && j < row.length - 1 ? usedArray[i - 1][j + 1] : '.';
+      const lowerLeft = i < usedArray.length - 1 && j > 0 ? usedArray[i + 1][j - 1] : '.';
+      const lowerRight = i < usedArray.length - 1 && j < row.length - 1 ? usedArray[i + 1][j + 1] : '.';
+      if (left === '.') {
+        openSides++;
+      }
+      if (right === '.') {
+        openSides++;
+      }
+      if (up === '.') {
+        openSides++;
+      }
+      if (down === '.') {
+        openSides++;
+      }
+      if (upperLeft === '.') {
+        openSides++;
+      }
+      if (upperRight === '.') {
+        openSides++;
+      }
+      if (lowerLeft === '.') {
+        openSides++;
+      }
+      if (lowerRight === '.') {
+        openSides++;
+      }
+      if (openSides >= 5) {
+        sum++;
+      }
+    }
+  }
+}
+
+console.timeEnd("part1");
+console.log(sum);
+
+
+// Part Two
+
+let usedArray2 = [];
+if (sampleMode) {
+  usedArray2 = [].concat(sampleArray);
+} else {
+  usedArray2 = [].concat(inputArray);
+}
+
+console.time("part2");
+let sum2 = 0;
+let done = false;
+
+while (!done) {
+  getOpenSides(sum2, usedArray2);
+}
+
+console.timeEnd("part2");
+console.log(sum2);
+
+// functions
+
+function getOpenSides(startingSum, usedArray) {
+  const newSum = JSON.parse(JSON.stringify(startingSum));
+  for (let i = 0; i < usedArray.length; i++) {
+    let row = [...usedArray[i].split('')];
+    for (let j = 0; j < row.length; j++) {
+      let cell = row[j];
+      if (cell === '@') {
+        let openSides = 0;
+        const left = j > 0 ? row[j - 1] : '.';
+        const right = j < row.length - 1 ? row[j + 1] : '.';
+        const up = i > 0 ? usedArray[i - 1][j] : '.';
+        const down = i < usedArray.length - 1 ? usedArray[i + 1][j] : '.';
+        const upperLeft = i > 0 && j > 0 ? usedArray[i - 1][j - 1] : '.';
+        const upperRight = i > 0 && j < row.length - 1 ? usedArray[i - 1][j + 1] : '.';
+        const lowerLeft = i < usedArray.length - 1 && j > 0 ? usedArray[i + 1][j - 1] : '.';
+        const lowerRight = i < usedArray.length - 1 && j < row.length - 1 ? usedArray[i + 1][j + 1] : '.';
+        if (left === '.') {
+          openSides++;
+        }
+        if (right === '.') {
+          openSides++;
+        }
+        if (up === '.') {
+          openSides++;
+        }
+        if (down === '.') {
+          openSides++;
+        }
+        if (upperLeft === '.') {
+          openSides++;
+        }
+        if (upperRight === '.') {
+          openSides++;
+        }
+        if (lowerLeft === '.') {
+          openSides++;
+        }
+        if (lowerRight === '.') {
+          openSides++;
+        }
+        if (openSides >= 5) {
+          sum2++;
+          row[j] = '.';
+        }
+      }
+    }
+    usedArray[i] = row.join('');
+  }
+
+  if (sum2 === newSum) {
+    done = true;
+  }
+}
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