Merge pull request #429 from JBtje/master

- Added: public methods with information and examples to readme

Readme.md

@@ -184,6 +184,102 @@ form.submit({
 });
 ```
 
+### Methods
+
+- [_Void_ append( **String** _field_, **Mixed** _value_ [, **Mixed** _options_] )](https://github.com/form-data/form-data#void-append-string-field-mixed-value--mixed-options-).
+- [_Array_ getHeaders( [**Array** _userHeaders_] )](https://github.com/form-data/form-data#array-getheaders-array-userheaders-)
+- [_String_ getBoundary()](https://github.com/form-data/form-data#string-getboundary)
+- [_Buffer_ getBuffer()](https://github.com/form-data/form-data#buffer-getbuffer)
+- [_Integer_ getLengthSync()](https://github.com/form-data/form-data#integer-getlengthsync)
+- [_Integer_ getLength( **function** _callback_ )](https://github.com/form-data/form-data#integer-getlength-function-callback-)
+- [_Boolean_ hasKnownLength()](https://github.com/form-data/form-data#boolean-hasknownlength)
+- [_Request_ submit( _params_, **function** _callback_ )](https://github.com/form-data/form-data#request-submit-params-function-callback-)
+- [_String_ toString()](https://github.com/form-data/form-data#string-tostring)
+
+#### _Void_ append( **String** _field_, **Mixed** _value_ [, **Mixed** _options_] )
+Append data to the form. You can submit about any format (string, integer, boolean, buffer, etc.). However, Arrays are not supported and need to be turned into strings by the user.
+```javascript
+var form = new FormData();
+form.append( 'my_string', 'my value' );
+form.append( 'my_integer', 1 );
+form.append( 'my_boolean', true );
+form.append( 'my_buffer', new Buffer(10) );
+form.append( 'my_array_as_json', JSON.stringify( ['bird','cute'] ) )
+```
+
+You may provide a string for options, or an object.
+```javascript
+// Set filename by providing a string for options
+form.append( 'my_file', fs.createReadStream('/foo/bar.jpg'), 'bar.jpg' );
+
+// provide an object.
+form.append( 'my_file', fs.createReadStream('/foo/bar.jpg'), {filename: 'bar.jpg', contentType: 'image/jpeg', knownLength: 19806} );
+```
+
+#### _Array_ getHeaders( [**Array** _userHeaders_] )
+This method ads the correct `content-type` header to the provided array of `userHeaders`.  
+
+#### _String_ getBoundary()
+Return the boundary of the formData. A boundary consists of 26 `-` followed by 24 numbers
+for example:
+```javascript
+--------------------------515890814546601021194782
+```
+_Note: The boundary must be unique and may not appear in the data._
+
+#### _Buffer_ getBuffer()
+Return the full formdata request package, as a Buffer. You can insert this Buffer in e.g. Axios to send multipart data.
+
+```javascript
+var form = new FormData();
+form.append( 'my_buffer', Buffer.from([0x4a,0x42,0x20,0x52,0x6f,0x63,0x6b,0x73]) );
+form.append( 'my_file', fs.createReadStream('/foo/bar.jpg') );
+
+axios.post( 'https://example.com/path/to/api',
+            form.getBuffer(),
+            form.getHeaders()
+          )
+```
+
+#### _Integer_ getLengthSync()
+Same as `getLength` but synchronous.
+
+_Note: getLengthSync __doesn't__ calculate streams length._
+
+#### _Integer_ getLength( **function** _callback_ )
+Returns the `Content-Length` async. The callback is used to handle errors and continue once the length has been calculated
+```javascript
+this.getLength(function(err, length) {
+  if (err) {
+    this._error(err);
+    return;
+  }
+
+  // add content length
+  request.setHeader('Content-Length', length);
+
+  ...
+}.bind(this));
+```
+
+#### _Boolean_ hasKnownLength()
+Checks if the length of added values is known.
+
+#### _Request_ submit( _params_, **function** _callback_ )
+Submit the form to a web application.
+```javascript
+var form = new FormData();
+form.append( 'my_string', 'Hello World' );
+
+form.submit( 'http://example.com/', function(err, res) {
+  // res – response object (http.IncomingMessage)  //
+  res.resume();
+} );
+```
+
+#### _String_ toString()
+Returns the form data as a string. Don't use this if you are sending files or buffers, use `getBuffer()` instead.
+
 ### Integration with other libraries
 
 #### Request