Revert "Fixed isFormData predicate; (#4413)" (#4472)

This reverts commit 73e3bdb883.

index.d.ts

@@ -107,9 +107,6 @@ export interface AxiosRequestConfig<D = any> {
   transitional?: TransitionalOptions;
   signal?: AbortSignal;
   insecureHTTPParser?: boolean;
-  env?: {
-    FormData?: new (...args: any[]) => object;
-  };
 }
 
 export interface HeadersDefaults {

lib/adapters/http.js

@@ -87,9 +87,7 @@ module.exports = function httpAdapter(config) {
       headers['User-Agent'] = 'axios/' + VERSION;
     }
 
-    if (utils.isFormData(data) && utils.isFunction(data.getHeaders)) {
-      Object.assign(headers, data.getHeaders());
-    } else if (data && !utils.isStream(data)) {
+    if (data && !utils.isStream(data)) {
       if (Buffer.isBuffer(data)) {
         // Nothing to do...
       } else if (utils.isArrayBuffer(data)) {

lib/defaults.js

@@ -3,7 +3,6 @@
 var utils = require('./utils');
 var normalizeHeaderName = require('./helpers/normalizeHeaderName');
 var enhanceError = require('./core/enhanceError');
-var toFormData = require('./helpers/toFormData');
 
 var DEFAULT_CONTENT_TYPE = {
   'Content-Type': 'application/x-www-form-urlencoded'
@@ -72,17 +71,10 @@ var defaults = {
       setContentTypeIfUnset(headers, 'application/x-www-form-urlencoded;charset=utf-8');
       return data.toString();
     }
-
-    var isObjectPayload = utils.isObject(data);
-    var contentType = headers && headers['Content-Type'];
-
-    if ( isObjectPayload && contentType === 'multipart/form-data' ) {
-      return toFormData(data,  new (this.env && this.env.FormData || FormData));
-    } else if ( isObjectPayload || contentType === 'application/json' ) {
+    if (utils.isObject(data) || (headers && headers['Content-Type'] === 'application/json')) {
       setContentTypeIfUnset(headers, 'application/json');
       return stringifySafely(data);
     }
-
     return data;
   }],
 
@@ -120,8 +112,6 @@ var defaults = {
   maxContentLength: -1,
   maxBodyLength: -1,
 
-  env: {},
-
   validateStatus: function validateStatus(status) {
     return status >= 200 && status < 300;
   },

lib/helpers/toFormData.js

@@ -1,7 +1,5 @@
 'use strict';
 
-var utils = require('../utils');
-
 function combinedKey(parentKey, elKey) {
   return parentKey + '.' + elKey;
 }
@@ -13,7 +11,7 @@ function buildFormData(formData, data, parentKey) {
     });
   } else if (
     typeof data === 'object' &&
-    !(utils.isFile(data) || data === null)
+    !(data instanceof File || data === null)
   ) {
     Object.keys(data).forEach(function buildObject(key) {
       buildFormData(
@@ -46,12 +44,10 @@ function buildFormData(formData, data, parentKey) {
  * type FormVal = FormDataNest | FormDataPrimitive
  *
  * @param {FormVal} data
- * @param {?Object} formData
  */
 
-module.exports = function getFormData(data, formData) {
-  // eslint-disable-next-line no-param-reassign
-  formData = formData || new FormData();
+module.exports = function getFormData(data) {
+  var formData = new FormData();
 
   buildFormData(formData, data);
 

lib/utils.js

@@ -47,6 +47,15 @@ function isArrayBuffer(val) {
   return toString.call(val) === '[object ArrayBuffer]';
 }
 
+/**
+ * Determine if a value is a FormData
+ *
+ * @param {Object} val The value to test
+ * @returns {boolean} True if value is an FormData, otherwise false
+ */
+function isFormData(val) {
+  return toString.call(val) === '[object FormData]';
+}
 
 /**
  * Determine if a value is a view on an ArrayBuffer
@@ -159,21 +168,6 @@ function isStream(val) {
   return isObject(val) && isFunction(val.pipe);
 }
 
-/**
- * Determine if a value is a FormData
- *
- * @param {Object} thing The value to test
- * @returns {boolean} True if value is an FormData, otherwise false
- */
-function isFormData(thing) {
-  var pattern = '[object FormData]';
-  return thing && (
-    (typeof FormData === 'function' && thing instanceof FormData) ||
-    toString.call(thing) === pattern ||
-    (isFunction(thing.toString) && thing.toString() === pattern)
-  );
-}
-
 /**
  * Determine if a value is a URLSearchParams object
  *

test/specs/helpers/toFormData.spec.js

@@ -1,7 +1,7 @@
 var toFormData = require("../../../lib/helpers/toFormData");
 
 describe("toFormData", function () {
-  it("Convert nested data object to FormData", function () {
+  it("Convert nested data object to FormDAta", function () {
     var o = {
       val: 123,
       nested: {