Added conditional get support for client script middleware

 * The client script is now served conditionnaly based on the request
   headers. This means that if the browser sends a conditional request
   and the current body is fresh, we send a not modified response. Otherwise,
   we send the request as usual.

index.js

@@ -1,28 +1,52 @@
 "use strict";
 
-var fs   = require("fs");
-var path = require("path");
+var etag  = require("etag")
+var fresh = require("fresh")
+var fs    = require("fs");
+var path  = require("path");
 
-var script = path.resolve(__dirname + "/dist/index.min.js");
+var minifiedScript = path.resolve(__dirname + "/dist/index.min.js");
+var unminifiedScript = path.resolve(__dirname + "/dist/index.js");
 
-function init(options, connector, type) {
-
-    var result;
-
-    if (options && options.minify) {
-        result = fs.readFileSync(script);
-    } else {
-        script = path.resolve(__dirname + "/dist/index.js");
-        result = fs.readFileSync(script);
-    }
+function headers(res, body){
+    res.setHeader("Cache-Control", "public, max-age=0");
+    res.setHeader("Content-Type", "text/javascript");
+    res.setHeader("ETag", etag(body));
+};
+
+function body(options, connector) {
+  var script = minifiedScript;
+  if (options && !options.minify) {
+      script = unminifiedScript;
+  }
+
+  return connector + fs.readFileSync(script);
+}
+
+function isConditionalGet(req) {
+    return req.headers["if-none-match"] || req.headers["if-modified-since"];
+}
+
+function notModified(res) {
+    res.removeHeader("Content-Type");
+    res.statusCode = 304;
+    res.end();
+}
 
+function init(options, connector, type) {
+    var requestBody = body(options, connector);
     if (type && type === "file") {
-        return connector + result;
+        return requestBody;
     }
 
     return function (req, res) {
-        res.setHeader("Content-Type", "text/javascript");
-        res.end(connector + result);
+        headers(res, requestBody);
+
+        if (isConditionalGet(req) && fresh(req.headers, res._headers)) {
+            return notModified(res);
+        }
+
+        res.end(requestBody);
     };
 }
 

package.json

@@ -51,5 +51,8 @@
     "vinyl-source-stream": "^1.1.0"
   },
   "keywords": [],
-  "dependencies": {}
+  "dependencies": {
+    "etag": "^1.7.0",
+    "fresh": "^0.3.0"
+  }
 }

test/middleware/middleware.js

@@ -19,10 +19,47 @@ describe("Using the middleware", function () {
         assert.isFunction(index.middleware);
     });
 
-    it("should return the JS", function (done) {
+    it("should return the JS when no cache", function (done) {
         request(app)
             .get("/client")
             .expect("Content-Type", /text\/javascript/)
+            .expect("Cache-Control", "public, max-age=0")
+            .expect("ETag", /".*-.*"/)
+            .expect(200)
+            .end(function (err, res) {
+                assert.isTrue(res.text.length > 0);
+                assert.isTrue(res.text.indexOf("BEFORE") > -1);
+                done();
+            });
+    });
+
+    it("should return not modified if has cache and fresh", function (done) {
+        var etag = null;
+        request(app)
+            .get("/client")
+            .end(function (err, res) {
+                etag = res.headers["ETag"];
+            });
+
+        request(app)
+            .get("/client")
+            .set("If-None-Match", etag)
+            .expect("Cache-Control", "public, max-age=0")
+            .expect("ETag", /".*-.*"/)
+            .expect(304)
+            .end(function (err, res) {
+                assert.isUndefined(res.headers["Content-Type"]);
+                done();
+            });
+    });
+
+    it("should return the JS if has cache and not fresh", function (done) {
+        request(app)
+            .get("/client")
+            .set("If-None-Match", "Different-ETag")
+            .expect("Content-Type", /text\/javascript/)
+            .expect("Cache-Control", "public, max-age=0")
+            .expect("ETag", /".*-.*"/)
             .expect(200)
             .end(function (err, res) {
                 assert.isTrue(res.text.length > 0);