Improved FormData support; (#4448)

* Fixed isFormData predicate;
Added support for automatic object serialization to FormData if `Content-Type` is `multipart/form-data`;
Added support for FormData to be overloaded using `config.env.FormData` option;
Added support for FormData in node.js environment through `form-data` package;

* Added the `form-data` package as a dependency for the server build;
Added tests for FormData payload;

* Added FormData automatic serialization section;
Refactored cancellation section;

* Reworked toFormData helper;
Expose toFormData helper as a static method;
Refactored transform request;
Added kindOf, kindOfTest, endsWith, isTypedArray util;
Refactored utils.js to use kindOf for tests;

* Fixed isFormData predicate; (#4413)

Added support for automatic object serialization to FormData if `Content-Type` is `multipart/form-data`;
Added support for FormData to be overloaded using `config.env.FormData` option;
Added support for FormData in node.js environment using `form-data` package;

(cherry picked from commit 73e3bdb883)

* Added shortcut methods `postForm`, `putForm`, `patchForm` to submit a Form;
Added ability to submit FileList object as a FormData;
Updated README.md;

* Updated README.md;

test/specs/utils/endsWith.js

@@ -0,0 +1,10 @@
+var kindOf = require('../../../lib/utils').kindOf;
+
+describe('utils::kindOf', function () {
+  it('should return object tag', function () {
+    expect(kindOf({})).toEqual('object');
+    // cached result
+    expect(kindOf({})).toEqual('object');
+    expect(kindOf([])).toEqual('array');
+  });
+});

test/specs/utils/isX.spec.js

@@ -77,4 +77,9 @@ describe('utils::isX', function () {
     expect(utils.isURLSearchParams(new URLSearchParams())).toEqual(true);
     expect(utils.isURLSearchParams('foo=1&bar=2')).toEqual(false);
   });
+
+  it('should validate TypedArray instance', function () {
+    expect(utils.isTypedArray(new Uint8Array([1, 2, 3]))).toEqual(true);
+    expect(utils.isTypedArray([1, 2, 3])).toEqual(false);
+  });
 });

test/specs/utils/kindOf.js

@@ -0,0 +1,10 @@
+var kindOfTest = require('../../../lib/utils').kindOfTest;
+
+describe('utils::endsWith', function () {
+  it('should return true if the string ends with passed substring', function () {
+    var test = kindOfTest('number');
+
+    expect(test(123)).toEqual(true);
+    expect(test('123')).toEqual(false);
+  });
+});

test/specs/utils/kindOfTest.js

@@ -0,0 +1,10 @@
+var kindOf = require('../../../lib/utils').kindOf;
+
+describe('utils::kindOf', function () {
+  it('should return object tag', function () {
+    expect(kindOf({})).toEqual('object');
+    // cached result
+    expect(kindOf({})).toEqual('object');
+    expect(kindOf([])).toEqual('array');
+  });
+});

test/specs/utils/toArray.js

@@ -0,0 +1,10 @@
+var toArray = require('../../../lib/utils').toArray;
+
+describe('utils::kindOf', function () {
+  it('should return object tag', function () {
+    expect(toArray()).toEqual(null);
+    expect(toArray([])).toEqual([]);
+    expect(toArray([1])).toEqual([1]);
+    expect(toArray([1, 2, 3])).toEqual([1, 2, 3]);
+  });
+});