✨ Singleton

Author: tangweikun

src/creational/singleton/Sample-3.js

@@ -1,7 +1,7 @@
 const Cat = (function() {
   let instance
   return function() {
-    if (typeof instance !== 'object') {
+    if (!instance) {
       instance = this
     }
     return instance

src/creational/singleton/Sample-4.js

@@ -0,0 +1,18 @@
+// 用代理实现单例模式
+
+function Cat() {}
+
+const ProxyCat = (function() {
+  let instance
+  return function() {
+    if (!instance) {
+      instance = new Cat()
+    }
+    return instance
+  }
+})()
+
+/*============== 测试代码 ===============*/
+const cat1 = new ProxyCat()
+const cat2 = new ProxyCat()
+console.log(cat1 === cat2) // true