refactor: migrate into individual .js files

dragdrop.js

@@ -0,0 +1,25 @@
+const dropContainer = document.getElementById("dropcontainer");
+const fileInput = document.getElementById("input-file");
+
+dropContainer.addEventListener(
+  "dragover",
+  (e) => {
+    // prevent default to allow drop
+    e.preventDefault();
+  },
+  false
+);
+
+dropContainer.addEventListener("dragenter", () => {
+  dropContainer.classList.add("drag-active");
+});
+
+dropContainer.addEventListener("dragleave", () => {
+  dropContainer.classList.remove("drag-active");
+});
+
+dropContainer.addEventListener("drop", (e) => {
+  e.preventDefault();
+  dropContainer.classList.remove("drag-active");
+  fileInput.files = e.dataTransfer.files;
+});