problems(js): add “2700. Differences Between Two Objects”

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/js/differences-between-two-objects.js

@@ -0,0 +1,29 @@
+/**
+ * @param {object} obj1
+ * @param {object} obj2
+ * @return {object}
+ */
+function objDiff(obj1, obj2) {
+    if (obj1 === obj2) {
+        return {};
+    }
+
+    if (
+        obj1 === null || obj2 === null
+        || typeof obj1 !== 'object' || typeof obj2 !== 'object'
+        || Array.isArray(obj1) !== Array.isArray(obj2)
+    ) {
+        return [obj1, obj2];
+    }
+
+    let result = {};
+    for (let key in obj1) {
+        if (key in obj2) {
+            let diff = objDiff(obj1[key], obj2[key]);
+            if (Object.keys(diff).length) {
+                result[key] = diff;
+            }
+        }
+    }
+    return result;
+};