More proxy handlers

Author: tshemsedinov

JavaScript/4-has.js

@@ -0,0 +1,34 @@
+'use strict';
+
+const data = { name: 'Marcus Aurelius', city: 'Rome', born: 121 };
+
+const person = new Proxy(data, {
+  has(obj, key) {
+    console.log('check', key);
+    return (key in obj || key === 'age');
+  },
+  get(obj, key) {
+    console.log('get', key);
+    if (key === 'age') {
+      return (
+        new Date().getFullYear() -
+        new Date(obj.born + '').getFullYear()
+      );
+    }
+    return obj[key];
+  }
+});
+
+console.log('Try \'age\' in person');
+if ('age' in person) {
+  console.log('Try person.age');
+  if (person.age) {
+    console.log('Try person[\'age\']');
+    if (person['age']) {
+      console.log({
+        born: person.born,
+        age: person.age
+      });
+    }
+  }
+}

JavaScript/5-delete.js

@@ -0,0 +1,14 @@
+'use strict';
+
+const data = { name: 'Marcus Aurelius', city: 'Rome', born: 121 };
+
+const person = new Proxy(data, {
+  deleteProperty(obj, key) {
+    console.log('delete', key);
+    return true;
+  }
+});
+
+console.log(person);
+delete person.name;
+console.log(person);