Fixes #377, renders the html that can be manipulated with writer

utilities.go

@@ -2,6 +2,7 @@ package goquery
 
 import (
 	"bytes"
+	"io"
 
 	"golang.org/x/net/html"
 )
@@ -57,6 +58,16 @@ func nodeName(node *html.Node) string {
 	}
 }
 
+// Render renders the html of the first element from selector and writes it to the writer.
+// // It behaves the same as OuterHtml but writes to w instead of returning the string.
+func Render(w io.Writer, s *Selection) error {
+	if s.Length() == 0 {
+		return nil
+	}
+	n := s.Get(0)
+	return html.Render(w, n)
+}
+
 // OuterHtml returns the outer HTML rendering of the first item in
 // the selection - that is, the HTML including the first element's
 // tag and attributes.
@@ -66,12 +77,7 @@ func nodeName(node *html.Node) string {
 // a property provided by the DOM).
 func OuterHtml(s *Selection) (string, error) {
 	var buf bytes.Buffer
-
-	if s.Length() == 0 {
-		return "", nil
-	}
-	n := s.Get(0)
-	if err := html.Render(&buf, n); err != nil {
+	if err := Render(&buf, s); err != nil {
 		return "", err
 	}
 	return buf.String(), nil

utilities_test.go

@@ -80,7 +80,6 @@ func TestNodeNameMultiSel(t *testing.T) {
 		t.Errorf("want %v, got %v", in, out)
 	}
 }
-
 func TestOuterHtml(t *testing.T) {
 	doc, err := NewDocumentFromReader(strings.NewReader(allNodes))
 	if err != nil {