initial commit

src/features/counter/Counter.js

@@ -0,0 +1,60 @@
+import React, { useState } from 'react';
+import { useSelector, useDispatch } from 'react-redux';
+import {
+  decrement,
+  increment,
+  incrementByAmount,
+  incrementAsync,
+  selectCount,
+} from './counterSlice';
+import styles from './Counter.module.css';
+
+export function Counter() {
+  const count = useSelector(selectCount);
+  const dispatch = useDispatch();
+  const [incrementAmount, setIncrementAmount] = useState('2');
+
+  return (
+    <div>
+      <div className={styles.row}>
+        <button
+          className={styles.button}
+          aria-label="Increment value"
+          onClick={() => dispatch(increment())}
+        >
+          +
+        </button>
+        <span className={styles.value}>{count}</span>
+        <button
+          className={styles.button}
+          aria-label="Decrement value"
+          onClick={() => dispatch(decrement())}
+        >
+          -
+        </button>
+      </div>
+      <div className={styles.row}>
+        <input
+          className={styles.textbox}
+          aria-label="Set increment amount"
+          value={incrementAmount}
+          onChange={e => setIncrementAmount(e.target.value)}
+        />
+        <button
+          className={styles.button}
+          onClick={() =>
+            dispatch(incrementByAmount(Number(incrementAmount) || 0))
+          }
+        >
+          Add Amount
+        </button>
+        <button
+          className={styles.asyncButton}
+          onClick={() => dispatch(incrementAsync(Number(incrementAmount) || 0))}
+        >
+          Add Async
+        </button>
+      </div>
+    </div>
+  );
+}

src/features/counter/Counter.module.css

@@ -0,0 +1,74 @@
+.row {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.row:not(:last-child) {
+  margin-bottom: 16px;
+}
+
+.value {
+  font-size: 78px;
+  padding-left: 16px;
+  padding-right: 16px;
+  margin-top: 2px;
+  font-family: 'Courier New', Courier, monospace;
+}
+
+.button {
+  appearance: none;
+  background: none;
+  font-size: 32px;
+  padding-left: 12px;
+  padding-right: 12px;
+  outline: none;
+  border: 2px solid transparent;
+  color: rgb(112, 76, 182);
+  padding-bottom: 4px;
+  cursor: pointer;
+  background-color: rgba(112, 76, 182, 0.1);
+  border-radius: 2px;
+  transition: all 0.15s;
+}
+
+.textbox {
+  font-size: 32px;
+  padding: 2px;
+  width: 64px;
+  text-align: center;
+  margin-right: 8px;
+}
+
+.button:hover, .button:focus {
+  border: 2px solid rgba(112, 76, 182, 0.4);
+}
+
+.button:active {
+  background-color: rgba(112, 76, 182, 0.2);
+}
+
+.asyncButton {
+  composes: button;
+  position: relative;
+  margin-left: 8px;
+}
+
+.asyncButton:after {
+  content: "";
+  background-color: rgba(112, 76, 182, 0.15);
+  display: block;
+  position: absolute;
+  width: 100%;
+  height: 100%;
+  left: 0;
+  top: 0;
+  opacity: 0;
+  transition: width 1s linear, opacity 0.5s ease 1s;
+}
+
+.asyncButton:active:after {
+  width: 0%;
+  opacity: 1;
+  transition: 0s
+}

src/features/counter/counterSlice.js

@@ -0,0 +1,42 @@
+import { createSlice } from '@reduxjs/toolkit';
+
+export const counterSlice = createSlice({
+  name: 'counter',
+  initialState: {
+    value: 0,
+  },
+  reducers: {
+    increment: state => {
+      // Redux Toolkit allows us to write "mutating" logic in reducers. It
+      // doesn't actually mutate the state because it uses the Immer library,
+      // which detects changes to a "draft state" and produces a brand new
+      // immutable state based off those changes
+      state.value += 1;
+    },
+    decrement: state => {
+      state.value -= 1;
+    },
+    incrementByAmount: (state, action) => {
+      state.value += action.payload;
+    },
+  },
+});
+
+export const { increment, decrement, incrementByAmount } = counterSlice.actions;
+
+// The function below is called a thunk and allows us to perform async logic. It
+// can be dispatched like a regular action: `dispatch(incrementAsync(10))`. This
+// will call the thunk with the `dispatch` function as the first argument. Async
+// code can then be executed and other actions can be dispatched
+export const incrementAsync = amount => dispatch => {
+  setTimeout(() => {
+    dispatch(incrementByAmount(amount));
+  }, 1000);
+};
+
+// The function below is called a selector and allows us to select a value from
+// the state. Selectors can also be defined inline where they're used instead of
+// in the slice file. For example: `useSelector((state) => state.counter.value)`
+export const selectCount = state => state.counter.value;
+
+export default counterSlice.reducer;