Add getPageNumbers function for retrieving page numbers array

src/utils/getPageNumbers.ts

@@ -0,0 +1,13 @@
+const getPageNumbers = (numberOfPosts: number) => {
+  const numberOfPages =
+    numberOfPosts / Number(import.meta.env.PUBLIC_POST_PER_PAGE);
+
+  let pageNumbers: number[] = [];
+  for (let i = 1; i <= Math.ceil(numberOfPages); i++) {
+    pageNumbers = [...pageNumbers, i];
+  }
+
+  return pageNumbers;
+};
+
+export default getPageNumbers;