1 files changed, 16 insertions, 5 deletions
diff --git a/misc.go b/misc.go
index dce9dac..84d2ae1 100644
--- a/misc.go
+++ b/misc.go
@@ -67,7 +67,13 @@ const (
 	BackslashEscapeUnicode
 )
 
-func EscapeJSSafe(c rune, _ BackslashEscapeMode) BackslashEscapeMode {
+type BackslashEscaper = func(rune, BackslashEscapeMode) BackslashEscapeMode
+
+func EscapePreserve(_ rune, wasEscaped BackslashEscapeMode) BackslashEscapeMode {
+	return wasEscaped
+}
+
+func EscapeJSSafe(c rune, wasEscaped BackslashEscapeMode) BackslashEscapeMode {
 	// JSON is notionally a JS subset, but that's not actually
 	// true.
 	//
@@ -76,7 +82,7 @@ func EscapeJSSafe(c rune, _ BackslashEscapeMode) BackslashEscapeMode {
 	case '\u2028', '\u2029':
 		return BackslashEscapeUnicode
 	default:
-		return BackslashEscapeNone
+		return wasEscaped
 	}
 }
 
@@ -98,8 +104,13 @@ func EscapeDefault(c rune, wasEscaped BackslashEscapeMode) BackslashEscapeMode {
 	}
 }
 
-func EscapePreserve(_ rune, wasEscaped BackslashEscapeMode) BackslashEscapeMode {
-	return wasEscaped
+func EscapeDefaultNonHTMLSafe(c rune, wasEscaped BackslashEscapeMode) BackslashEscapeMode {
+	switch c {
+	case '\b', '\f', utf8.RuneError:
+		return BackslashEscapeUnicode
+	default:
+		return EscapeJSSafe(c, wasEscaped)
+	}
 }
 
 func writeStringUnicodeEscape(w io.Writer, c rune) (int, error) {
@@ -134,7 +145,7 @@ func writeStringShortEscape(w io.Writer, c rune) (int, error) {
 	buf := [2]byte{'\\', b}
 	return w.Write(buf[:])
 }
-func writeStringChar(w io.Writer, c rune, wasEscaped BackslashEscapeMode, escaper func(rune, BackslashEscapeMode) BackslashEscapeMode) (int, error) {
+func writeStringChar(w io.Writer, c rune, wasEscaped BackslashEscapeMode, escaper BackslashEscaper) (int, error) {
 	if escaper == nil {
 		escaper = EscapeDefault
 	}