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DaveCeddia Hook useReducer example
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| // https://www.youtube.com/watch?v=sYDFCuZHrqw&list=PL-F_CAUJfW9Xbg5l4PGknlRqur9oT_8Go&index=2 | |
| // DaveCeddia Hook useReducer example | |
| import React, { useReducer } from "react"; | |
| import ReactDOM from "react-dom/client"; | |
| import "./index.css"; | |
| const inlineStyle = { | |
| display: "flex", | |
| flexDirection: "column", | |
| justifyContent: "space-around", | |
| alignItems: "center", | |
| height: "90px", | |
| width: "210px", | |
| fontSize: "24px", | |
| margin: "30px", | |
| fontWeight: "bold", | |
| border: "1px solid black", | |
| padding: "10px", | |
| }; | |
| const buttons = { | |
| display: "flex", | |
| justifyContent: "space-between", | |
| width: "210px", | |
| }; | |
| const button = { | |
| display: "flex", | |
| justifyContent: "center", | |
| alignItems: "center", | |
| width: "90px", | |
| height: "30px", | |
| }; | |
| const number = { | |
| display: "flex", | |
| justifyContent: "center", | |
| }; | |
| const Count = () => { | |
| const [count, dispatch] = useReducer((state, action) => { | |
| switch (action) { | |
| case "+": | |
| return state + 1; | |
| case "-": | |
| return state - 1; | |
| default: | |
| return state; | |
| } | |
| }, 0); | |
| return ( | |
| <div style={inlineStyle}> | |
| <span style={number}>{count}</span> | |
| <div style={buttons}> | |
| <button style={button} onClick={() => dispatch("-")}> | |
| Decrement | |
| </button> | |
| <button style={button} onClick={() => dispatch("+")}> | |
| Increment | |
| </button> | |
| </div> | |
| </div> | |
| ); | |
| }; | |
| const root = ReactDOM.createRoot(document.getElementById("root")); | |
| root.render(<Count />); |
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| // https://www.youtube.com/watch?v=sYDFCuZHrqw&list=PL-F_CAUJfW9Xbg5l4PGknlRqur9oT_8Go&index=2 | |
| // DaveCeddia Hook useReducer more complex example | |
| import React, { useReducer, useRef } from "react"; | |
| import ReactDOM from "react-dom/client"; | |
| import "./index.css"; | |
| const ShoppingList = () => { | |
| const inputRef = useRef(); | |
| const [items, dispatch] = useReducer((state, action) => { | |
| switch (action.type) { | |
| case "add": | |
| return [...state, { id: Math.random().toString(), name: action.name }]; | |
| case "remove": | |
| return state.filter((_, index) => index !== action.index); | |
| case "clear": | |
| return []; | |
| default: | |
| return state; | |
| } | |
| }, []); | |
| const handleSubmit = (event) => { | |
| event.preventDefault(); | |
| dispatch({ | |
| type: "add", | |
| name: inputRef.current.value, | |
| }); | |
| inputRef.current.value = ""; | |
| }; | |
| return ( | |
| <> | |
| <form onSubmit={handleSubmit}> | |
| <input ref={inputRef} /> | |
| </form> | |
| <button onClick={() => dispatch({ type: "clear" })}>Clear</button> | |
| <ul> | |
| {items.map((item, index) => ( | |
| <li key={item.id}> | |
| {item.name}{" "} | |
| <button onClick={() => dispatch({ type: "remove", index })}> | |
| X | |
| </button> | |
| </li> | |
| ))} | |
| </ul> | |
| </> | |
| ); | |
| }; | |
| const root = ReactDOM.createRoot(document.getElementById("root")); | |
| root.render(<ShoppingList />); |
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