add redux starter code

.gitignore

@@ -1,4 +1,5 @@
 tik-tak-toe/node_modules
 tik-tak-toe/.DS_Store
 react-essentials/node_modules
-calculator/node_modules
+calculator/node_modules
+redux/node_modules

redux/package.json

@@ -0,0 +1,16 @@
+{
+  "name": "redux",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "type": "commonjs",
+  "dependencies": {
+    "redux": "^5.0.1"
+  }
+}

redux/redux-demo.js

@@ -0,0 +1,29 @@
+const redux = require("redux");
+
+const counterReducer = (state = { counter: 0 }, action) => {
+  if (action.type === "increment") {
+    return {
+      counter: state.counter + 1,
+    };
+  }
+
+  if (action.type === "decrement") {
+    return {
+      counter: state.counter - 1,
+    };
+  }
+
+  return state;
+};
+
+const store = redux.createStore(counterReducer);
+
+const counterSubscriber = () => {
+  const latestState = store.getState();
+  console.log(latestState);
+};
+
+store.subscribe(counterSubscriber);
+
+store.dispatch({ type: "increment" });
+store.dispatch({ type: "decrement" });