use static js

static/js/csv_download.js

@@ -0,0 +1,3 @@
+function saveCsv(csvString) {
+
+}

static/js/img_preview.js

@@ -0,0 +1,9 @@
+let imgPreview = document.getElementById('img-preview');
+let imgUpload = document.getElementById('img-upload');
+imgUpload.onchange = event => {
+    const [file] = imgUpload.files;
+    if (file) {
+        console.log(file)
+        imgPreview.src = URL.createObjectURL(file);
+    }
+};