From 66603815971fc7a7606906bc3ffc6bf9508daf0f Mon Sep 17 00:00:00 2001
From: Amit Portnoy <amit.portnoy@gmail.com>
Date: Tue, 14 Feb 2017 11:10:39 +0200
Subject: [PATCH] don't read to file when the browser cache is valid

---
 index.js | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/index.js b/index.js
index abd883c..01db2c7 100644
--- a/index.js
+++ b/index.js
@@ -116,13 +116,19 @@ function send(ctx, path, opts) {
     }
 
     if (setHeaders) setHeaders(ctx.res, path, stats);
-
-    // stream
-    ctx.set('Content-Length', stats.size);
+  
     if (!ctx.response.get('Last-Modified')) ctx.set('Last-Modified', stats.mtime.toUTCString());
     if (!ctx.response.get('Cache-Control')) ctx.set('Cache-Control', 'max-age=' + (maxage / 1000 | 0));
-    ctx.type = type(path);
-    ctx.body = fs.createReadStream(path);
+    if (ctx.fresh) {
+      // the browser has a valid cache for this file
+      ctx.status = 304;
+      ctx.body = null;
+    } else {
+      // stream
+      ctx.set('Content-Length', stats.size);
+      ctx.type = type(path);
+      ctx.body = fs.createReadStream(path);
+    }
 
     return path;
   });