[WIP] refactor(data): camelCase keys in jqLite#data

This change aligns jqLite with jQuery 3.

Author: mgol

src/jqLite.js

@@ -383,6 +383,7 @@ function jqLiteExpandoStore(element, createIfNecessary) {
 
 function jqLiteData(element, key, value) {
   if (jqLiteAcceptsData(element)) {
+    var prop;
 
     var isSimpleSetter = isDefined(value);
     var isSimpleGetter = !isSimpleSetter && key && !isObject(key);
@@ -391,16 +392,18 @@ function jqLiteData(element, key, value) {
     var data = expandoStore && expandoStore.data;
 
     if (isSimpleSetter) { // data('key', value)
-      data[key] = value;
+      data[camelCase(key)] = value;
     } else {
       if (massGetter) {  // data()
         return data;
       } else {
         if (isSimpleGetter) { // data('key')
           // don't force creation of expandoStore if it doesn't exist yet
-          return data && data[key];
+          return data && data[camelCase(key)];
         } else { // mass-setter: data({key1: val1, key2: val2})
-          extend(data, key);
+          for (prop in key) {
+            data[camelCase(prop)] = key[prop];
+          }
         }
       }
     }

test/jqLiteSpec.js

@@ -594,6 +594,39 @@ describe('jqLite', function() {
         }).not.toThrow();
       });
     });
+
+    fdescribe('camelCasing keys', function() {
+      // jQuery 2.x has different behavior; skip the tests.
+      // if (isJQuery2x()) return;
+
+      it('should camelCase the key in a setter', function() {
+        var element = jqLite(a);
+
+        element.data('a-B-c-d-42--e', 'z-x');
+        expect(element.data()).toEqual({'a-BCD-42-E': 'z-x'});
+      });
+
+      it('should camelCase the key in a getter', function() {
+        var element = jqLite(a);
+
+        element.data()['a-BCD-42-E'] = 'x-c';
+        expect(element.data('a-B-c-d-42--e')).toBe('x-c');
+      });
+
+      it('should camelCase the key in a mass setter', function() {
+        var element = jqLite(a);
+
+        element.data({'a-B-c-d-42--e': 'c-v', 'r-t-v': 42});
+        expect(element.data()).toEqual({'a-BCD-42-E': 'c-v', 'rTV': 42});
+      });
+
+      it('should ignore non-camelCase keys in the data in a getter', function() {
+        var element = jqLite(a);
+
+        element.data()['a-b'] = 'b-n';
+        expect(element.data('a-b')).toBe(undefined);
+      });
+    });
   });