React實戰教程之從零開始手把手教你使用 React 最新特性Hooks API 打造一款計算機知識測驗App

[豆約翰]發表於2020-06-24
ReactHookAPI計算機APP

專案演示地址

專案演示地址

專案程式碼結構

前言

React 框架的優雅不言而喻，元件化的程式設計思想使得React框架開發的專案程式碼簡潔，易懂，但早期 React 類元件的寫法略顯繁瑣。React Hooks 是 React 16.8 釋出以來最吸引人的特性之一，她簡化了原有程式碼的編寫，是未來 React 應用的主流寫法。

本文通過一個實戰小專案，手把手從零開始帶領大家快速入門React Hooks。

在本專案中，會用到以下知識點：

  • React 元件化設計思想
  • React State 和 Props
  • React 函式式元件的使用
  • React Hooks useState 的使用
  • React Hooks useEffect 的使用
  • React 使用 Axios 請求遠端介面獲取問題及答案
  • React 使用Bootstrap美化介面

Hello React

（1）安裝node.js 官網連結

（2）安裝vscode 官網連結

（3）安裝 creat-react-app 功能元件，該元件可以用來初始化一個專案， 即按照一定的目錄結構，生成一個新專案。
開啟cmd 視窗 輸入：

npm install --g create-react-app 
npm install --g yarn

（-g 代表全域性安裝）

如果安裝失敗或較慢。需要換源，可以使用淘寶NPM映象，設定方法為：

npm config set registry https://registry.npm.taobao.org

設定完成後，重新執行

npm install --g create-react-app
npm install --g yarn

（4）在你想建立專案的目錄下 例如 D:/project/ 開啟cmd命令 輸入

create-react-app react-exam

去使用creat-react-app命令建立名字是react-exam的專案

安裝完成後，移至新建立的目錄並啟動專案

cd react-exam
yarn start

一旦執行此命令，localhost:3000新的React應用程式將彈出一個新視窗。

專案目錄結構

右鍵react-exam目錄，使用vscode開啟該目錄。
react-exam專案目錄中有一個/public和/src目錄，以及node_modules，.gitignore，README.md，和package.json。

在目錄/public中，重要檔案是index.html，其中一行程式碼最重要

<div id="root"></div>

該div做為我們整個應用的掛載點

/src目錄將包含我們所有的React程式碼。

要檢視環境如何自動編譯和更新您的React程式碼，請找到檔案/src/App.js：
將其中的

        <a
          className="App-link"
          href="https://reactjs.org"
          target="_blank"
          rel="noopener noreferrer"
        >
          Learn React
        </a>

修改為

        <a
          className="App-link"
          href="https://reactjs.org"
          target="_blank"
          rel="noopener noreferrer"
        >
          和豆約翰 Learn React
        </a>

儲存檔案後，您會注意到localhost:3000編譯並重新整理了新資料。

React-Exam專案實戰

1. 首頁製作

1.安裝專案依賴，在package.json中新增：

  "dependencies": {
    "@testing-library/jest-dom": "^4.2.4",
    "@testing-library/react": "^9.3.2",
    "@testing-library/user-event": "^7.1.2",
    "react": "^16.13.1",
    "react-dom": "^16.13.1",
    "react-scripts": "3.4.1",
    "axios": "^0.19.2",
    "bootstrap": "^4.5.0",
    "he": "^1.2.0",
    "react-loading": "^2.0.3",
    "reactstrap": "^8.4.1"
  },

執行命令：

yarn install

修改index.js，匯入bootstrap樣式

import "bootstrap/dist/css/bootstrap.min.css";

修改App.css程式碼

html {
  width: 80%;
  margin-left: 10%;
  margin-top: 2%;
}

.ansButton {
  margin-right: 4%;
  margin-top: 4%;
}

修改App.js,引入Quiz元件

import React from 'react';
import './App.css'
import { Quiz } from './Exam/Quiz';

function App() {
  return (
    <div className = 'layout'>
    <Quiz></Quiz>
    </div>
  );
}

export default App;

在專案src目錄下新增Exam目錄，Exam目錄中新建Quiz.js

Quiz元件的定義如下：
Quiz.js，引入開始頁面元件Toggle。

import React, { useState } from "react";
import { Toggle } from "./Toggle";
export const Quiz = () => {
  const [questionData, setQuestionData] = useState([]);
  const questions = questionData.map(({ question }) => [question]);
  const answers = questionData.map(({ incorrect_answers, correct_answer }) =>
    [correct_answer, incorrect_answers].flat()
  );
  return (
    <>
      <Toggle
        setQuestionData={setQuestionData}
      />
    </>
  );
};

Toggle.js，點選開始按鈕，通過axios訪問遠端介面，獲得題目及答案。

import React from "react";
import axios from "axios";
import ToggleHeader from "./ToggleHeader";
import {
  Button,
  Form,
} from "reactstrap";

export const Toggle = ({
  setQuestionData,
}) => {
  const getData = async () => {
    try {
      const incomingData = await axios.get(
        `https://opentdb.com/api.php?amount=10&category=18&difficulty=easy&type=multiple`
      );
      setQuestionData(incomingData.data.results);
    } catch (err) {
      console.error(err);
    }
  };

  return (
    <>
      <ToggleHeader />
      <Form
        onSubmit={(e) => {
          e.preventDefault();
          getData();
        }}
      >
        <Button color="primary">開始</Button>
      </Form>
    </>
  );
};

ToggleHeader.js

import React from "react";
import { Jumbotron, Container} from "reactstrap";

export default function ToggleHeader() {
  return (
    <Jumbotron fluid>
      <Container fluid>
        <h1 className="display-4">計算機知識小測驗</h1>
      </Container>
    </Jumbotron>
  );
}

https://opentdb.com/api.php介面返回的json資料格式為

{
	"response_code": 0,
	"results": [{
		"category": "Science: Computers",
		"type": "multiple",
		"difficulty": "easy",
		"question": "The numbering system with a radix of 16 is more commonly referred to as ",
		"correct_answer": "Hexidecimal",
		"incorrect_answers": ["Binary", "Duodecimal", "Octal"]
	}, {
		"category": "Science: Computers",
		"type": "multiple",
		"difficulty": "easy",
		"question": "This mobile OS held the largest market share in 2012.",
		"correct_answer": "iOS",
		"incorrect_answers": ["Android", "BlackBerry", "Symbian"]
	}, {
		"category": "Science: Computers",
		"type": "multiple",
		"difficulty": "easy",
		"question": "How many values can a single byte represent?",
		"correct_answer": "256",
		"incorrect_answers": ["8", "1", "1024"]
	}, {
		"category": "Science: Computers",
		"type": "multiple",
		"difficulty": "easy",
		"question": "In computing, what does MIDI stand for?",
		"correct_answer": "Musical Instrument Digital Interface",
		"incorrect_answers": ["Musical Interface of Digital Instruments", "Modular Interface of Digital Instruments", "Musical Instrument Data Interface"]
	}, {
		"category": "Science: Computers",
		"type": "multiple",
		"difficulty": "easy",
		"question": "In computing, what does LAN stand for?",
		"correct_answer": "Local Area Network",
		"incorrect_answers": ["Long Antenna Node", "Light Access Node", "Land Address Navigation"]
	}]
}

程式執行效果：

當前專案目錄結構為：

2. 問題展示頁面

Quiz.js，新增toggleView變數用來切換檢視。

  const [toggleView, setToggleView] = useState(true);

Quiz.js，其中Question和QuestionHeader 元件，參見後面。

import { Question } from "./Question";
import { Jumbotron } from "reactstrap";
import QuestionHeader from "./QuestionHeader";

...
export const Quiz = () => {
  var [index, setIndex] = useState(0);
  const [questionData, setQuestionData] = useState([]);
...
 return (
    <>
      {toggleView && (
        <Toggle
          setIndex={setIndex}
          setQuestionData={setQuestionData}
          setToggleView={setToggleView}
        />
      )}
       {!toggleView &&
        (
          <Jumbotron>
            <QuestionHeader
              setToggleView={setToggleView}
            />
            <Question question={questions[index]} />
          </Jumbotron>
        )}
    </>
  );

使用index控制題目索引

var [index, setIndex] = useState(0);

修改Toggle.js
獲取完遠端資料，通過setToggleView(false);切換檢視。

export const Toggle = ({
  setQuestionData,
  setToggleView,
  setIndex,
}) => {
  
...

  return (
    <>
      <ToggleHeader />
      <Form
        onSubmit={(e) => {
          e.preventDefault();
          getData();
          setToggleView(false);
          setIndex(0);
        }}
      >
        <Button color="primary">開始</Button>
      </Form>
    </>
  );
};

QuestionHeader.js程式碼：
同樣的，點選 返回首頁按鈕 setToggleView(true)，切換檢視。

import React from "react";
import { Button } from "reactstrap";
export default function QuestionHeader({ setToggleView, category }) {
  return (
    <>
      <Button color="link" onClick={() => setToggleView(true)}>
        返回首頁
      </Button>
    </>
  );
}

Question.js程式碼
接受父元件傳過來的question物件，並顯示。
其中he.decode是對字串中的特殊字元進行轉義。

import React from "react";
import he from "he";
export const Question = ({ question }) => {
  // he is a oddly named library that decodes html into string values

  var decode = he.decode(String(question));

  return (
    <div>
      <hr className="my-2" />
      <h1 className="display-5">
        {decode}
      </h1>
      <hr className="my-2" />
      <br />
    </div>
  );
};

程式執行效果：
首頁

點選開始後，顯示問題：

當前專案目錄結構為：
image.png

3. 載入等待動畫

新增LoadingSpin.js

import React from "react";
import { Spinner } from "reactstrap";
export default function LoadingSpin() {
  return (
    <>
      <Spinner type="grow" color="primary" />
      <Spinner type="grow" color="secondary" />
      <Spinner type="grow" color="success" />
      <Spinner type="grow" color="danger" />
    </>
  );
}

修改Quiz.js


import LoadingSpin from "./LoadingSpin";

export const Quiz = () => {

  const [isLoading, setLoading] = useState(false);


  return (
    <>
      {toggleView && (
        <Toggle
          ...
          setLoading={setLoading}
        />
      )}
      {!toggleView &&
        (isLoading ? (
          <LoadingSpin />
        ) : 
        (
          ...
        ))}
    </>
  );
};

修改Toggle.js



export const Toggle = ({
...
  setLoading,
}) => {
  const getData = async () => {
    try {
      setLoading(true);
      const incomingData = await axios.get(
        `https://opentdb.com/api.php?amount=10&category=18&difficulty=easy&type=multiple`
      );
      setQuestionData(incomingData.data.results);
      setLoading(false);
    } catch (err) {
      console.error(err);
    }
  };

 ...
};

執行效果：

目前程式碼結構：
image.png

4. 實現下一題功能

新增Answer.js，使用者點選下一題按鈕，修改index，觸發主介面重新整理，顯示下一題：

import React from "react";
import { Button } from "reactstrap";

export const Answer = ({ setIndex, index }) => {
  function answerResult() {
    setIndex(index + 1);
  }

  return (
    <Button className="ansButton" onClick={answerResult}>
      下一題
    </Button>
  );
};

修改Quiz.js，新增Answer元件：

import { Answer } from "./Answer";
...
 {!toggleView &&
        (isLoading ? (
          <LoadingSpin />
        ) : 
        (
          <Jumbotron>
            ...
            <Answer
            setIndex={setIndex}
            index={index}
            />
          </Jumbotron>

        ))}

執行效果：

點選下一題：

相關文章