Check if the two operands are of the same type before interpreting a missing prop as a remove op

.travis.yml

@@ -1,4 +1,7 @@
 language: node_js
+dist: trusty
+before_script:
+  - npm install
 node_js: 8
 script:
   - npm test && npm run bench

src/duplex.ts

@@ -187,8 +187,10 @@ function _generate(mirror, obj, patches, path) {
   for (var t = oldKeys.length - 1; t >= 0; t--) {
     var key = oldKeys[t];
     var oldVal = mirror[key];
+
     if (hasOwnProperty(obj, key) && !(obj[key] === undefined && oldVal !== undefined && Array.isArray(obj) === false)) {
       var newVal = obj[key];
+
       if (typeof oldVal == "object" && oldVal != null && typeof newVal == "object" && newVal != null) {
         _generate(oldVal, newVal, patches, path + "/" + escapePathComponent(key));
       }
@@ -199,9 +201,12 @@ function _generate(mirror, obj, patches, path) {
         }
       }
     }
-    else {
+    else if(Array.isArray(mirror) === Array.isArray(obj)) {
       patches.push({ op: "remove", path: path + "/" + escapePathComponent(key) });
       deleted = true; // property has been deleted
+    } else {
+      patches.push({ op: "replace", path, value: obj });
+      changed = true;
     }
   }
 

test/spec/duplexSpec.js

@@ -1426,8 +1426,47 @@ describe('duplex', function() {
       }, 20);
     });
   });
-
   describe('compare', function() {
+    it('Replacing a root array with an object should be handled well', function() {
+
+      const obj = {};
+      var patches = jsonpatch.compare(['jack'], obj);
+      expect(patches).toEqual([
+        {
+          op: 'replace',
+          path: '',
+          value: obj
+        }
+      ]);
+
+    });
+    it('Replacing an array with an object should be handled well', function() {
+
+      const obj = {};
+      var patches = jsonpatch.compare({arr: ['jack']}, {arr: obj});
+      expect(patches).toEqual([
+        {
+          op: 'replace',
+          path: '/arr',
+          value: obj
+        }
+      ]);
+
+    });
+    it('Replacing an array that nested in an object with an object nested in an an object should be handled well', function() {
+
+      const obj = {};
+      var patches = jsonpatch.compare({arr: {deeperArray: ['jack']}}, {arr: {deeperArray: obj}});
+
+      expect(patches).toEqual([
+        {
+          op: 'replace',
+          path: '/arr/deeperArray',
+          value: obj
+        }
+      ]);
+
+    });
     it('should return an add for a property that does not exist in the first obj', function() {
       var objA = {
         user: {