Use res.headersSent when available

closes #15
pillarjs · Sep 22, 2017 · e249491 · e249491
1 parent ed4c24d
commit e249491
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diff --git a/HISTORY.md b/HISTORY.md
@@ -1,3 +1,8 @@
+unreleased
+==========
+
+  * Use `res.headersSent` when available
+
 1.0.6 / 2017-09-22
 ==================
 

diff --git a/index.js b/index.js
@@ -89,7 +89,7 @@ function finalhandler (req, res, options) {
     var status
 
     // ignore 404 on in-flight response
-    if (!err && res._header) {
+    if (!err && headersSent(res)) {
       debug('cannot 404 after headers sent')
       return
     }
@@ -125,7 +125,7 @@ function finalhandler (req, res, options) {
     }
 
     // cannot actually respond
-    if (res._header) {
+    if (headersSent(res)) {
       debug('cannot %d after headers sent', status)
       req.socket.destroy()
       return
@@ -227,6 +227,20 @@ function getResponseStatusCode (res) {
   return status
 }
 
+/**
+ * Determine if the response headers have been sent.
+ *
+ * @param {object} res
+ * @returns {boolean}
+ * @private
+ */
+
+function headersSent (res) {
+  return typeof res.headersSent !== 'boolean'
+    ? Boolean(res._header)
+    : res.headersSent
+}
+
 /**
  * Send response.
  *