Add a ton of JS algo snippets (#56)

utilities/javascript/matrixTraverse.js

@@ -0,0 +1,28 @@
+function traverse(matrix) {
+    const DIRECTIONS = [[0, 1], [0, -1], [1, 0], [-1, 0]];
+    const rows = matrix.length, cols = matrix[0].length;
+    const visited = matrix.map(row => Array(row.length).fill(false));
+    function dfs(i, j) {
+        if (visited[i][j]) {
+            return;
+        }
+        visited[i][j] = true;
+        DIRECTIONS.forEach(dir => {
+            const row = i + dir[0], col = j + dir[1];
+            // Boundary check.
+            if (row < 0 || row >= rows || col < 0 || col >= cols) {
+                return;
+            }
+            // Valid neighbor check.
+            if (matrix[row][col] !== 1) {
+                return;
+            }
+            dfs(row, col);
+        });
+    }
+    for (let i = 0; i < rows; i++) {
+        for (let j = 0; j < cols; j++) {
+            dfs(i, j);
+        }
+    }
+}