simplify normalize function

replace normalize function to only use 3 replace rules instead of 6

lib/url-join.js

@@ -4,14 +4,18 @@
   else context[name] = definition();
 })('urljoin', this, function () {
 
-  function normalize (str) {
-    return str
-            .replace(/^\/\//g, '://')   // replace leading // with :/
-            .replace(/[\/]+/g, '/')     // flatten multiple occurencies of / to single /
-            .replace(/\/\?/g, '?')      // remove trailing / before parameters
-            .replace(/\/\#/g, '#')      // remove trailing / before hash
-            .replace(/\:\//g, '://')    // replace :/ with ://
-            .replace(/^:\/\//g , '//'); // replace leading :// with //
+  function normalize (str, options) {
+
+    // make sure protocol is followed by two slashes
+    str = str.replace(/:\//g, '://');
+
+    // remove consecutive slashes
+    str = str.replace(/([^:\s])\/+/g, '$1/');
+
+    // remove trailing slash before parameters or hash
+    str = str.replace(/\/(\?|#)/g, '$1');
+
+    return str;
   }
 
   return function () {

test/tests.js

@@ -11,6 +11,11 @@ describe('url join', function () {
       .should.eql('http://www.google.com/foo/bar?test=123');
   });
 
+  it('should be able to join protocol with slashes', function () {
+    urljoin('http://', 'www.google.com/', 'foo/bar', '?test=123')
+      .should.eql('http://www.google.com/foo/bar?test=123');
+  });
+
   it('should remove extra slashes', function () {
     urljoin('http:', 'www.google.com///', 'foo/bar', '?test=123')
       .should.eql('http://www.google.com/foo/bar?test=123');
@@ -21,8 +26,8 @@ describe('url join', function () {
       .should.eql('http://www.google.com/foo/bar?test=123#faaaaa');
   });
 
-  it('should keep leading //', function () {
+  it('should support protocol-relative urls', function () {
     urljoin('//www.google.com', 'foo/bar', '?test=123')
       .should.eql('//www.google.com/foo/bar?test=123')
-  })
+  });
 });