fixing .relativeTo() path comparison - closes #75

README.md

@@ -207,6 +207,8 @@ URI.js is published under the [MIT license](http://www.opensource.org/licenses/m
 
 ## Changelog ##
 
+* fixing [`relativeTo()`](http://medialize.github.com/URI.js/docs.htmlrelativeto) - ([Issue #75](https://github.com/medialize/URI.js/issues/75))
+
 ### 1.10.1 (April 2nd 2013) ###
 
 * adding [`absoluteTo()`](http://medialize.github.com/URI.js/docs.html#absoluteto) to properly resolve relative scheme - ([Issue #71](https://github.com/medialize/URI.js/issues/73))

src/URI.js

@@ -689,9 +689,9 @@ URI.commonPath = function(one, two) {
     if (pos < 1) {
         return one.charAt(0) === two.charAt(0) && one.charAt(0) === '/' ? '/' : '';
     }
-
+    
     // revert to last /
-    if (one.charAt(pos) !== '/') {
+    if (one.charAt(pos) !== '/' || two.charAt(pos) !== '/') {
         pos = one.substring(0, pos).lastIndexOf('/');
     }
 
@@ -1672,33 +1672,36 @@ p.relativeTo = function(base) {
     var properties = ['protocol', 'username', 'password', 'hostname', 'port'];
     var common, _base, _this, _base_diff, _this_diff;
 
-    if (this._parts.urn) {
+    if (relative._parts.urn) {
         throw new Error('URNs do not have any generally defined hierachical components');
     }
 
     if (!(base instanceof URI)) {
         base = new URI(base);
     }
 
-    if (this.path().charAt(0) !== '/' || base.path().charAt(0) !== '/') {
+    if (relative.path().charAt(0) !== '/' || base.path().charAt(0) !== '/') {
         throw new Error('Cannot calculate common path from non-relative URLs');
     }
 
     // determine common sub path
     common = URI.commonPath(relative.path(), base.path());
-
-    // no relation if there's nothing in common 
-    if (!common || common === '/') {
-        return relative;
-    }
 
     // relative paths don't have authority
     for (var i = 0, p; p = properties[i]; i++) {
         relative._parts[p] = null;
     }
+
+    // no relation if there's nothing in common 
+    if (common === '/') {
+        return relative;
+    } else if (!common) {
+        // there's absolutely nothing in common here
+        return this.clone();
+    }
 
     _base = base.directory();
-    _this = this.directory();
+    _this = relative.directory();
 
     // base and this are on the same level
     if (_base === _this) {

test/test.js

@@ -1004,6 +1004,21 @@ test("relativeTo", function() {
             url: '/base/path/with/subdir/inner.html',
             base: '/base/path/top.html',
             result: './with/subdir/inner.html'
+        }, {
+            name: 'absolute /',
+            url: 'http://example.org/foo/bar/bat',
+            base: 'http://example.org/',
+            result: '/foo/bar/bat'
+        }, {
+            name: 'absolute /foo',
+            url: 'http://example.org/foo/bar/bat',
+            base: 'http://example.org/foo',
+            result: '/foo/bar/bat'
+        }, {
+            name: 'absolute /foo/',
+            url: 'http://example.org/foo/bar/bat',
+            base: 'http://example.org/foo/',
+            result: './bar/bat'
         }
     ];