Added axios.formToJSON method; (#4735)

* Draft

* Added `formDataToJSON` helper;
Added `axios.formToJSON` method;
Added client tests;

Co-authored-by: Jay <jasonsaayman@gmail.com>

test/specs/helpers/formDataToJSON.spec.js

@@ -0,0 +1,50 @@
+var formDataToJSON = require('../../../lib/helpers/formDataToJSON');
+
+describe('formDataToJSON', function () {
+  it('should convert a FormData Object to JSON Object', function () {
+    const formData = new FormData();
+
+    formData.append('foo[bar][baz]', '123');
+
+    expect(formDataToJSON(formData)).toEqual({
+      foo: {
+        bar: {
+          baz: '123'
+        }
+      }
+    });
+  });
+
+  it('should convert repeatable values as an array', function () {
+    const formData = new FormData();
+
+    formData.append('foo', '1');
+    formData.append('foo', '2');
+
+    expect(formDataToJSON(formData)).toEqual({
+      foo: ['1', '2']
+    });
+  });
+
+  it('should convert props with empty brackets to arrays', function () {
+    const formData = new FormData();
+
+    formData.append('foo[]', '1');
+    formData.append('foo[]', '2');
+
+    expect(formDataToJSON(formData)).toEqual({
+      foo: ['1', '2']
+    });
+  });
+
+  it('should supported indexed arrays', function () {
+    const formData = new FormData();
+
+    formData.append('foo[0]', '1');
+    formData.append('foo[1]', '2');
+
+    expect(formDataToJSON(formData)).toEqual({
+      foo: ['1', '2']
+    });
+  });
+});

test/specs/instance.spec.js

@@ -25,7 +25,8 @@ describe('instance', function () {
         'isAxiosError',
         'VERSION',
         'default',
-        'toFormData'
+        'toFormData',
+        'formToJSON'
       ].indexOf(prop) > -1) {
         continue;
       }