adding toFormData

lib/helpers/toFormData.js

@@ -0,0 +1,55 @@
+'use strict';
+
+function combinedKey(parentKey, elKey) {
+  return parentKey + '.' + elKey;
+}
+
+function buildFormData(formData, data, parentKey) {
+  if (Array.isArray(data)) {
+    data.forEach(function buildArray(el, i) {
+      buildFormData(formData, el, combinedKey(parentKey, i));
+    });
+  } else if (
+    typeof data === 'object' &&
+    !(data instanceof File || data === null)
+  ) {
+    Object.keys(data).forEach(function buildObject(key) {
+      buildFormData(
+        formData,
+        data[key],
+        parentKey ? combinedKey(parentKey, key) : key
+      );
+    });
+  } else {
+    if (data === undefined) {
+      return;
+    }
+
+    var value =
+      typeof data === 'boolean' || typeof data === 'number'
+        ? data.toString()
+        : data;
+    formData.append(parentKey, value);
+  }
+}
+
+/**
+ * convert a data object to FormData
+ *
+ * type FormDataPrimitive = string | Blob | number | boolean
+ * interface FormDataNest {
+ *   [x: string]: FormVal
+ * }
+ *
+ * type FormVal = FormDataNest | FormDataPrimitive
+ *
+ * @param {FormVal} data
+ */
+
+module.exports = function getFormData(data) {
+  var formData = new FormData();
+
+  buildFormData(formData, data);
+
+  return formData;
+};