#23 - JavaScript

Author: Sac-Corts

Roadmap/23 - SINGLETON/javascript/Sac-Corts.js

@@ -0,0 +1,72 @@
+class Singleton {
+    constructor() {
+        if (Singleton.instance) {
+            return Singleton.instance;
+        }
+        this.data = "Singleton instance data";
+        Singleton.instance = this;
+        return this;
+    }
+
+    getData() {
+        return this.data;
+    }
+
+    static getInstance() {
+        if(!Singleton.instance) {
+            Singleton.instance = new Singleton();
+        }
+        return Singleton.instance;
+    }
+}
+
+const instance1 = Singleton.getInstance();
+console.log(instance1.getData());
+
+const instance2 = new Singleton();
+console.log(instance1 === instance2);
+
+// Extra Exercise //
+
+class UserSession {
+    constructor() {
+        if (UserSession.instance) {
+            return UserSession.instance;
+        }
+        this.user = null;
+        UserSession.instance = this;
+        return this;
+    }
+
+    static getInstance() {
+        if (!UserSession.instance) {
+            UserSession.instance = new UserSession();
+        }
+        return UserSession.instance;
+    }
+
+    setUser(id, username, name, email) {
+        this.user = { id, username, name, email };
+    }
+    
+    getUser() {
+        if (!this.user) {
+            return "There is no user in the session"
+        }
+        return this.user;
+    }
+
+    clearSession() {
+        this.user = null;
+    }
+}
+
+const session1 = UserSession.getInstance();
+session1.setUser(1, "Sac", "Isaac", "[email protected]");
+console.log(session1.getUser());
+
+const session2 = UserSession.getInstance();
+console.log(session1 === session2);
+
+session2.clearSession();
+console.log(session1.getUser());