Add check for null case in isObject method (#1)

src/index.js

@@ -1,10 +1,10 @@
-const isObject = o => typeof o === 'object';
+const isObject = o => o != null && typeof o === 'object';
 const isEmpty = o => Object.keys(o).length === 0;
 
 const diff = (lhs, rhs) => {
   if (lhs === rhs) return {};
 
-  if (!isObject(lhs) || !isObject(rhs) || rhs === null || lhs === null) return rhs;
+  if (!isObject(lhs) || !isObject(rhs)) return rhs;
 
   const rhsKeys = Object.keys(rhs);
 
@@ -23,4 +23,4 @@ const diff = (lhs, rhs) => {
   }, deletedValues);
 };
 
-export default diff;
+export default diff;

src/index.spec.js

@@ -43,6 +43,10 @@ describe('.diff', () => {
         expect(diff({ a: 1 }, { a: 2 })).to.deep.equal({ a: 2 });
       });
 
+      it('returns right hand side value when right hand side value is null', () => {
+        expect(diff({ a: 1 }, { a: null })).to.deep.equal({ a: null });
+      });
+
       it('returns subset of right hand side value when sibling objects differ', () => {
         expect(diff({ a: { b: 1 }, c: 2 }, { a: { b: 1 }, c: 3 })).to.deep.equal({ c: 3 });
       });
@@ -86,4 +90,4 @@ describe('.diff', () => {
       });
     });
   });
-});
+});