style: addressing some feedback from pr review

Author: erunion

src/helpers/form-data.js

@@ -22,6 +22,8 @@
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
+ *
+ * Extracted from https://github.com/node-fetch/node-fetch/blob/64c5c296a0250b852010746c76144cb9e14698d9/src/utils/form-data.js
  */
 
 const carriage = '\r\n'

src/index.js

@@ -5,6 +5,7 @@
 var debug = require('debug')('httpsnippet')
 var es = require('event-stream')
 var MultiPartForm = require('form-data')
+var FormDataPolyfill = require('form-data/lib/form_data')
 var qs = require('querystring')
 var reducer = require('./helpers/reducer')
 var targets = require('./targets')
@@ -122,7 +123,7 @@ HTTPSnippet.prototype.prepare = function (request) {
         // This hack is pretty awful but it's the only way we can use this library in the browser as if we code this
         // against just the native FormData object, we can't polyfill that back into Node because Blob and File objects,
         // which something like `formdata-polyfill` requires, don't exist there.
-        const isNativeFormData = (typeof form[Symbol.iterator] === 'function')
+        const isNativeFormData = !(form instanceof FormDataPolyfill)
 
         // easter egg
         const boundary = '---011000010111000001101001'
@@ -131,15 +132,19 @@ HTTPSnippet.prototype.prepare = function (request) {
         }
 
         request.postData.params.forEach(function (param) {
+          const name = param.name
+          const value = param.value || ''
+          const filename = param.fileName || null
+
           if (isNativeFormData) {
-            if (isBlob(param.value)) {
-              form.append(param.name, param.value || '', param.fileName || null)
+            if (isBlob(value)) {
+              form.append(name, value, filename)
             } else {
-              form.append(param.name, param.value || '')
+              form.append(name, value)
             }
           } else {
-            form.append(param.name, param.value || '', {
-              filename: param.fileName || null,
+            form.append(name, value, {
+              filename: filename,
               contentType: param.contentType || null
             })
           }