提取API无法加载file：/// C：/ Users / Jack / Desktop / Books_H / book-site / public / api / books。URL方案必须为“ http”或“ https”才能进行CORS请求

钱跃

2023-03-14

问题内容：

刚开始在我的学校学习node
js。他们给我们完成了一半任务，我需要使next和prev按钮起作用。但是，当我运行index.html时，控制台中会出现一些错误。错误是：

“获取API无法加载文件：/// C：/Users/Jack/Desktop/Books_H/book-
site/public/api/books。URL方案必须为“ http”或“ https”才能进行CORS请求。”

另一个是：

“未捕获（承诺）TypeError：无法在HTMLDocument.document.addEventListener处获取”。

我什至不知道如何开始解决这个问题。有什么帮助吗？

    <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=1000, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Hello</title>
</head>
<body>
    Hello from the other side! <b>Total: <span id="total"></span></b><br/>
    <button id="author">Sort by author</button>
    <button id="title">Sort by title</button>
    <table id="books" border="1">
        <tr>
            <th>
                Author
            </th>
            <th>
                Book Title
            </th>
        </tr>

    </table>
    <script src="index.js"></script>
</body>
</html>

Java脚本文件

    document.addEventListener("DOMContentLoaded", () => {
    processResponse(fetch("api/books"));

    document.getElementById("author").addEventListener("click", () =>{
        processResponse(fetch("api/books?sortby=author"))
    });

    document.getElementById("title").addEventListener("click", () =>{
        processResponse(fetch("api/books?sortby=title"))
    });

});

function processResponse(response) {
    let table = document.getElementById("books");
    let total = document.getElementById("total");

    response.then(data => data.json())
        .then(value => {
            table.innerHTML = "";
            const tr = document.createElement("tr");
            let th = document.createElement("th");
            th.innerHTML = "Author";
            tr.appendChild(th);
            th = document.createElement("th");
            th.innerHTML = "Book Title";
            tr.appendChild(th);
            table.appendChild(tr);
            for (let index = 0; index < value.books.length; index++) {
                const book = value.books[index];
                const tr = document.createElement("tr");
                let td = document.createElement("td");
                td.innerHTML = book.author;
                tr.appendChild(td);
                td = document.createElement("td");
                td.innerHTML = book.title;
                tr.appendChild(td);
                table.appendChild(tr);
            }
            total.innerHTML = value.total;
        });
}

server.js文件

    const fs = require('fs');
const express = require('express');
const app = express();

app.use(express.static("public"));

app.get("/", (req, res) => {
    res.sendFile("index.html", { root: __dirname + "/public" });
});

const apiRouter = express.Router();

apiRouter.get("/books", (req, res) => {

    let sortOrder = req.query["sortby"];

    fs.readFile("data/books.json", { encoding: 'utf8' }, (err, data) => {
        if (err) {
            console.error("ERROR is: ", err);
            return;
        }

        let books = JSON.parse(data);
        if (sortOrder === "author") {
            books.sort((a, b)=> a.author.localeCompare(b.author));
        } else if (sortOrder === "title") {
            books.sort((a, b)=> a.title.localeCompare(b.title));
        }

        res.send(JSON.stringify({
            books: books.slice(0, 50),
            total: books.length
        }));
    });
})

apiRouter.get("/books/title", (req, res) => {
    fs.readFile("data/books.json", { encoding: 'utf8' }, (err, data) => {
        if (err) {
            console.error("ERROR is: ", err);
            return;
        }

        let books = JSON.parse(data);
        let titles = books.map(book => book.title);
        res.send(JSON.stringify(titles));
    });
})

apiRouter.get("/books/author", (req, res) => {
    fs.readFile("data/books.json", { encoding: 'utf8' }, (err, data) => {
        if (err) {
            console.error("ERROR is: ", err);
            return;
        }

        let books = JSON.parse(data);
        let authors = books.map(book => book.author);
        res.send(JSON.stringify(authors));
    });
})


app.use("/api", apiRouter);


app.listen(8080, () => console.log('Example app listening on port 8080!'));

/*
And the books.json file that i guess you dont need so i wont post it.
My folder structure is:

Books > data Folder > books.json. 
Books > public Folder > index.html. 
Books > public Folder > index.js.
Books > server.js.
*/

问题答案：

好吧，这是我必须做的，如果它将来对所有人都有所帮助。这些都是基本的东西，但是我是初学者，所以我们开始吧。打开命令提示符。转到项目的目标位置（index.js文件所在的位置）并编写：

$ npm init -y
$ npm install -g express-generator
$ npm install express -S
$ npm install connect -S
$ npm install serve-static -S

然后转到server.js文件的目标并编写

$ node server.js

之后，我可以在浏览器中运行我的页面，在URL中键入http：// localhost：8080 /。

提取API无法加载file：/// C：/ Users / Jack / Desktop / Books_H / book-site / public / api / books。URL方案必须为“ http”或“ https”才能进行CORS请求

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