feat(fomdata): added support for spec-compliant FormData & Blob types; (#5316)

lib/helpers/toFormData.js

@@ -2,7 +2,8 @@
 
 import utils from '../utils.js';
 import AxiosError from '../core/AxiosError.js';
-import envFormData from '../env/classes/FormData.js';
+// temporary hotfix to avoid circular references until AxiosURLSearchParams is refactored
+import PlatformFormData from '../platform/node/classes/FormData.js';
 
 /**
  * Determines if the given thing is a array or js object.
@@ -59,17 +60,6 @@ const predicates = utils.toFlatObject(utils, {}, null, function filter(prop) {
   return /^is[A-Z]/.test(prop);
 });
 
-/**
- * If the thing is a FormData object, return true, otherwise return false.
- *
- * @param {unknown} thing - The thing to check.
- *
- * @returns {boolean}
- */
-function isSpecCompliant(thing) {
-  return thing && utils.isFunction(thing.append) && thing[Symbol.toStringTag] === 'FormData' && thing[Symbol.iterator];
-}
-
 /**
  * Convert a data object to FormData
  *
@@ -99,7 +89,7 @@ function toFormData(obj, formData, options) {
   }
 
   // eslint-disable-next-line no-param-reassign
-  formData = formData || new (envFormData || FormData)();
+  formData = formData || new (PlatformFormData || FormData)();
 
   // eslint-disable-next-line no-param-reassign
   options = utils.toFlatObject(options, {
@@ -117,7 +107,7 @@ function toFormData(obj, formData, options) {
   const dots = options.dots;
   const indexes = options.indexes;
   const _Blob = options.Blob || typeof Blob !== 'undefined' && Blob;
-  const useBlob = _Blob && isSpecCompliant(formData);
+  const useBlob = _Blob && utils.isSpecCompliantForm(formData);
 
   if (!utils.isFunction(visitor)) {
     throw new TypeError('visitor must be a function');