Simple proxy

Author: tshemsedinov

JavaScript/1-proxy.js

@@ -1,66 +1,51 @@
 'use strict';
 
-function Transaction() {}
-
-Transaction.start = (data) => {
+const start = (data) => {
   console.log('start transaction');
   let delta = {};
-
-  const methods = {
-    commit: () => {
-      console.log('commit transaction');
-      Object.assign(data, delta);
-      delta = {};
-    },
-    rollback: () => {
-      console.log('rollback transaction');
-      delta = {};
-    }
-  };
-
-  const proxy = new Proxy(data, {
-    get(target, key, proxy) {
-      if (key === Symbol.iterator) {
-        const changes = Object.keys(delta);
-        const keys = Object.keys(target).concat(changes);
-        const props = keys.filter((x, i, a) => a.indexOf(x) === i);
-        return props[Symbol.iterator]();
+  return new Proxy(data, {
+    get(target, key) {
+      if (key === 'commit') {
+        return () => {
+          console.log('commit transaction');
+          Object.assign(data, delta);
+          delta = {};
+        };
       }
-      if (methods.hasOwnProperty(key)) return methods[key];
       if (delta.hasOwnProperty(key)) return delta[key];
       return target[key];
     },
-    getOwnPropertyDescriptor: (target, key) => (
-      Object.getOwnPropertyDescriptor(
-        delta.hasOwnProperty(key) ? delta : target, key
-      )
-    ),
     set(target, key, val) {
       console.log('set', key, val);
       if (target[key] === val) delete delta[key];
       else delta[key] = val;
       return true;
     }
   });
-  return proxy;
 };
 
 // Usage
 
 const data = { name: 'Marcus Aurelius', city: 'Rome', born: 121 };
 
-const transaction = Transaction.start(data);
-console.dir(transaction);
+console.log('data.name', data.name);
+console.log('data.born', data.born);
+
+const transaction = start(data);
 
 transaction.name = 'Mao Zedong';
 transaction.born = 1893;
-console.dir({ data, transaction });
+
+console.log('data.name', data.name);
+console.log('data.born', data.born);
+
+console.log('transaction.name', transaction.name);
+console.log('transaction.born', transaction.born);
 
 transaction.commit();
-console.dir({ data, transaction });
 
-transaction.city = 'Shaoshan';
-console.dir({ data, transaction });
+console.log('data.name', data.name);
+console.log('data.born', data.born);
 
-transaction.rollback();
-console.dir({ data, transaction });
+console.log('transaction.name', transaction.name);
+console.log('transaction.born', transaction.born);