node访问路径返回网页文件

思路 根据 发送请求的路径 判断应该读区哪个文件夹中的哪个文件

例如
hongbin.xyz:3002/abc
应当返回 /zbc/index.html文件

html文件引入的index.css
请求的路径是hongbin.xyz:3000/index.css没办法确定css文件所属目录
应当返回 /zbc/index.css
问题： req.url是index.css怎么确定是/abc目录下的index.css文件
解决： req.headers.referer 是发起请求的地址 为hongbin.xyz:3002/abc
通过referer判断是哪个文件目录下的文件

css中的 background:url(./images/1.png)
应当返回 /zbc/images/1.png
但是发起请求的是index.css文件 referer为hongbin.xyz:3002/index.css
解决部署前换成 绝对地址 background:url(abc/images/1.png)
直接返回 abc/images/1.png

代码：

const express = require("express");
const fs = require("fs");
const http = require("http");
const app = express();
const path = require('path');

const port = process.env.PORT || 3000;


app.all("*", function (req, res, next) {
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "content-type,Authorization");
    res.header("Access-Control-Allow-Methods", "DELETE,PUT,POST,GET,OPTIONS");
    if (req.method.toLowerCase() == "options") res.status(200).send();
    else next();
});

const httpServer = http.createServer(app);

httpServer.listen(port, () => { console.log("> dev mode on http " + port) });

/**
* 包含的文件夹
* 只有请求路径在文件夹内才会返回文件
*/
let fileNames = fs.readdirSync('../source');

app.get('/updateFileDir', (req, res) => {
    fileNames = fs.readdirSync('../source');
    return res.json({ message: '更新成功', fileNames });
})



app.get("/*", (req, res, next) => {
    let pathName = req.url;
    pathName = pathName.substring(0, pathName.indexOf('?') === -1 ? pathName.length : pathName.indexOf('?'));
    const dirName = pathName.substring(1);
    console.log(pathName);
    let referer = req.headers?.referer ?? "";
    referer = referer.substring(0, referer.indexOf('?') === -1 ? referer.length : referer.indexOf('?'));
    const reqSource = referer.replace('http://' + req.headers.host, '');

    if (fileNames.includes(dirName)) {
        req.fileName = dirName;
        pathName += "/index.html";
    } else if (fileNames.includes(reqSource?.substring(1))) {
        pathName = `${reqSource}${pathName}`;
    } else {
        //处理background：url(./asset/*/xxxx.png) => /assets/*/xxxx.png
        //提交代码时需要转化成绝对地址 /4-11/assets/*/xxxx.png
        if (pathName.split('/')[1] && fileNames.includes(pathName.split('/')[1])) {
            console.log("绝对路径:", pathName);
        } else return res.status(404).json("未找到资源");
    }
    console.log(pathName);
    const extName = path.extname(pathName);
    fs.readFile(`../source${pathName}`, function (err, data) {
        if (err) {
            console.error(err);
            res.status(400).json(err);
        } else {
            const ext = getExt(extName);
            res.writeHead(200, { "Content-Type": ext + "; charset=utf-8" });
            res.write(data);
        }
        res.end();
    });
});



const EXT = {
    ".html": "text/html",
    ".css": "text/css",
    ".js": "text/js",
    ".ico": "image/x-icon",
    ".png": "image/png",
    ".svg": "image/svg",
};
// 获取后缀名
getExt = extName => {
    return EXT[extName];
};