问题描述
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 /。
解决方法
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",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",res) => {
fs.readFile("data/books.json",err);
return;
}
let books = JSON.parse(data);
let titles = books.map(book => book.title);
res.send(JSON.stringify(titles));
});
})
apiRouter.get("/books/author",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.
*/