Added ProjectEuler problem 8 with passed test cases

Project-Euler/Problem8.js

@@ -0,0 +1,26 @@
+// Problem: https://projecteuler.net/problem=8
+
+const largestAdjacentNumber = (grid, consecutive) => {
+  grid = grid.split('\n').join('');
+  const splitedGrid = grid.split("\n");
+  let largestProd = 0;
+
+  for (let row in splitedGrid) {
+    const currentRow = splitedGrid[row].split('').map(x => Number(x));
+
+    for (let i = 0; i < currentRow.length - consecutive; i++) {
+      const combine = currentRow.slice(i, i + consecutive);
+
+      if (!combine.includes(0)) {
+        const product = combine.reduce(function (a, b) {
+          return a * b
+        });
+
+        if (largestProd < product) largestProd = product;
+      }
+    }
+  }
+  return largestProd;
+}
+
+export { largestAdjacentNumber };