thank you gurke!

.vscode/settings.json

@@ -1,3 +1,4 @@
 {
-    "deno.enable": true
+    "deno.enable": true,
+    "editor.wordWrapColumn": 300
 }

solutions/04-a.ts

@@ -24,13 +24,11 @@ class DayFour implements Solvable {
         // start top right
 
         const getDiagonals = (mat: string[][]) => {
-            let [b,a] = [0, mat[0].length - 1]
+            let [b,a] = [0, 140 - 1]
             const lines = []
             while (b < mat.length) {
-
-
                 let line = ''
-                for (let [y,x] = [b,a]; x < mat[y].length && y < mat.length - 1; y++,x++)
+                for (let [y,x] = [b,a]; x < 140 && y < 140; y++,x++)
                     line += mat[y][x]
 
                 lines.push(line.split(''))

solutions/04-b.ts

@@ -0,0 +1,84 @@
+import { solvables } from "../main.ts";
+
+import type { Solvable } from "../solvable.ts";
+import { readInput } from "../utils.ts";
+
+class DayFour implements Solvable {
+    input = readInput('04')
+
+    public part1(): Solvable {
+
+        const transpose = (m: string[][]) => m[0].map((_, i) => m.map(x => x[i]))
+
+        const matrix = this.input.trim().split('\n').map(line => line.split(''))
+
+        function lookAround(x: number, y: number) {
+            const allowed = {
+                top: y >= 3,
+                bottom: y <= matrix.length - 4,
+                left: x >= 3,
+                right: x <= matrix.length - 4
+            }
+
+            const results = []
+            if (allowed.top) {
+                // top         
+                results.push(matrix[y][x] + matrix[y - 1][x] + matrix[y - 2][x] + matrix[y - 3][x])
+                if (allowed.left) {
+                    // topleft       
+                    results.push(matrix[y][x] + matrix[y - 1][x - 1] + matrix[y - 2][x - 2] + matrix[y - 3][x - 3])
+                }
+                if (allowed.right) {
+                    // topright      
+                    results.push(matrix[y][x] + matrix[y - 1][x + 1] + matrix[y - 2][x + 2] + matrix[y - 3][x + 3])
+                }
+            }
+
+            if (allowed.bottom) {
+                // bottom
+                results.push(matrix[y][x] + matrix[y + 1][x] + matrix[y + 2][x] + matrix[y + 3][x])
+                if (allowed.left) {
+                    // bottomleft    
+                    results.push(matrix[y][x] + matrix[y + 1][x - 1] + matrix[y + 2][x - 2] + matrix[y + 3][x - 3])
+                }
+                if (allowed.right) {
+                    // bottomright   
+                    results.push(matrix[y][x] + matrix[y + 1][x + 1] + matrix[y + 2][x + 2] + matrix[y + 3][x + 3])
+                }
+            }
+
+            if (allowed.left) {
+                // left        
+                results.push(matrix[y][x] + matrix[y][x - 1] + matrix[y][x - 2] + matrix[y][x - 3])
+            }
+            if (allowed.right) {
+                // right       
+                results.push(matrix[y][x] + matrix[y][x + 1] + matrix[y][x + 2] + matrix[y][x + 3])
+            }
+
+            return results
+        }
+
+        function countMatches(resultsArr: string[]): number {
+            return resultsArr.filter(result => result === 'XMAS').length
+        }
+
+        let amountOfMatches = 0
+        for (let y = 0; y < matrix.length; y++) {
+            for (let x = 0; x < matrix.length; x++) {
+                if (matrix[y][x] === 'X')
+                    amountOfMatches += countMatches(lookAround(x, y))
+            }
+        }
+
+        console.log(amountOfMatches)
+
+        return this
+    }
+
+    public part2(): Solvable {
+        return this
+    }
+}
+
+solvables.push(new DayFour())