Add support to specific route in express (#18)

A new option was added that allows to use a specific route
with the middleware provided by staticify.

This option is used by the `getVersionedPath` method.

The specified route for the middleware is added before the
versioned path. When a specific route is not used, the method
continues to function normally.

Author: jacsamg

README.md

@@ -59,6 +59,21 @@ Generate a short (7-digit) md5 hash instead of the full (32-digit) one.
 * Type: Boolean
 * Default: `true`
 
+### pathPrefix
+
+If you are using the staticify convenience middleware through a specific route, it is necessary to indicate the route in this option.
+
+* Type: String
+* Default: "/"
+
+```js
+var path = require('path');
+var options = { pathPrefix: '/assets' };
+var staticify = require('staticify')(path.join(__dirname, 'public'), options);
+
+app.use('/assets', staticify.middleware);  // `app` is your express instance
+```
+
 ### sendOptions
 
 * Type: Object

index.js

@@ -17,6 +17,7 @@ const staticify = (root, options) => {
         let defaultOptions = {
             includeAll: opts.includeAll || false,
             shortHash: opts.shortHash || true,
+            pathPrefix: opts.pathPrefix || '/',
             sendOptions: opts.sendOptions || {}
         };
 
@@ -74,7 +75,7 @@ const staticify = (root, options) => {
 
         fileNameParts.push(versions[p], fileNameParts.pop());
 
-        return path.posix.join(path.dirname(p), fileNameParts.join('.'));
+        return path.posix.join(opts.pathPrefix, path.dirname(p), fileNameParts.join('.'));
     };
 
     // index.<hash>.js -> index.js

test/index.js

@@ -60,6 +60,17 @@ describe('.getVersionedPath', () => {
         /^[0-9a-f]{32}$/i.exec(versioned[1])[0].should.equal(versioned[1]);
     });
 
+    it('should add a prefix route to the path', () => {
+        let versioned = staticify(ROOT, {pathPrefix: '/prefix'}).getVersionedPath('/index.js');
+
+        versioned = versioned.split('.');
+        versioned.should.have.a.lengthOf(3);
+        versioned[0].should.equal('/prefix/index');
+        versioned[2].should.equal('js');
+        versioned[1].should.have.a.lengthOf(7);
+        /^[0-9a-f]{7}$/i.exec(versioned[1])[0].should.equal(versioned[1]);
+    });
+
     it('shouldn\'t add a hash if the path isn\'t known', () => {
         staticify(ROOT).getVersionedPath('/unknown.js').should.equal('/unknown.js');
     });