Restructure javascript

app/static/js/Requests/Requests.js

@@ -0,0 +1,37 @@
+Requests = {};
+
+Requests.JSONfetch = (input, init={}) => {
+  return new Promise((resolve, reject) => {
+    let fixedInit = {};
+    fixedInit.headers = {};
+    fixedInit.headers['Accept'] = 'application/json';
+    if (init.hasOwnProperty('body')) {
+      fixedInit.headers['Content-Type'] = 'application/json';
+    }
+    fetch(input, Utils.mergeObjectsDeep(init, fixedInit))
+      .then(
+        (response) => {
+          response.json()
+            .then(
+              (json) => {
+                let message = json.message || json;
+                let category = json.category || 'message';
+                app.flash(message, category);
+              },
+              (error) => {
+                app.flash(`[${response.status}]: ${response.statusText}`, 'error');
+              }
+            );
+          if (response.ok) {
+            resolve(response);
+          } else {
+            reject(response);
+          }
+        },
+        (response) => {
+          app.flash('Something went wrong', 'error');
+          reject(response);
+        }
+      );
+  });
+};