gojs

https://gojs.net/latest/learn/

GoJS is a JavaScript library for implementing interactive diagrams. This page will show you the essentials of using GoJS. We assume you are a programmer who is familiar with HTML, CSS, and JavaScript.

https://gojs.net/latest/samples/

Node.js v14.2.0 文档

http://nodejs.cn/api/

简易上传功能index.js

const http = require('http');
const fs = require('fs');
const path = require('path');
var url = require("url");
const app = http.createServer();
const port = 3000;
const ROOT_DIR = process.cwd();


const upload_page = `
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>upload</title>
</head>

<body>
    <form action="/" method="post" enctype="multipart/form-data">
        <input type="file" name="file" id="file" />
        <br />
        <input type="submit" name="submit" value="Submit" />
    </form>
</body>

</html>
`

function transfile(filepath, res) {
    const stream = fs.createReadStream(filepath);
    stream.pipe(res);

}

function save_file(filepath, filename, buf, callback) {
    const write_file = function () {
        filestream = fs.createWriteStream(path.join(filepath, filename));
        filestream.write(buf);
        let msg = `${filename} saved.\n`;
        callback(null, msg);
    }

    // Check if the file exists in the current directory, and if it is writable.
    fs.access(filepath, fs.constants.F_OK | fs.constants.W_OK, (err) => {
        if (err) {
            if (err.code === 'ENOENT') {
                fs.mkdir(filepath, (err, fd) => {
                    if (err) {
                        callback(err)
                    }else{
                        write_file();
                    }
                })
            } else {
                console.error('is read-only');
                callback(err);
            }

        } else {
            write_file();
        }
    });

}

function readDir(filepath, callback) {
    fs.readdir(filepath, (err, files) => {
        callback(err, files);
    });
}
function show_upload_page(req, res) {
    res.end(upload_page);
}

function show_files(req, res) {
    var urlpath = url.parse(req.url).pathname;

    var filepath = path.join(ROOT_DIR, urlpath);
    fs.stat(filepath, (err, stats) => {
        if (err) {
            res.end(JSON.stringify(err));
        } else if (stats.isFile()) {
            //download file content.
            var filestream = fs.createReadStream(filepath);
            res.writeHead(200, { 'Content-disposition': 'attachment; filename=' + path.basename(filepath) }); //here you can specify file name
            filestream.pipe(res); // also you can set content-type
        } else if (stats.isDirectory()) {
            //list files.
            readDir(filepath, (err, files) => {
                res.end(JSON.stringify(files));
            });
        }
    });
}



const http_get = function (req, res) {
    var urlpath = url.parse(req.url).pathname;
    if (urlpath == '/upload') {
        show_upload_page(req, res);
    } else {
        show_files(req, res);
    }

}

const get_part = function (str, prefix, suffix) {
    let begin = str.indexOf(prefix);
    if (begin < 0) {
        return null;
    }
    begin = begin + prefix.length;

    let end = str.length;
    if (suffix) {
        end = str.indexOf(suffix, begin);
    }
    if (end < 0) {
        return null;
    }
    return str.substring(begin, end);
}

const http_post = function (req, res) {

    var urlpath = url.parse(req.url).pathname;
    var filepath = path.join(ROOT_DIR, urlpath);
    // const stream = fs.createReadStream(filepath);
    var content_type_header = req.headers['content-type']
    if (!content_type_header) {
        res.end("wrong content-type");
    }
    var boundary = get_part(content_type_header, 'boundary=');
    if (!boundary) {
        console.log("no boundary");
        res.end();
        return;
    }

    let chunks = [];

    // Readable streams emit 'data' events once a listener is added.
    req.on('data', (chunk) => {
        chunks.push(chunk);
    });

    // The 'end' event indicates that the entire body has been received.
    req.on('end', () => {
        try {

            let head = '--' + boundary;
            let delimiter = '\r\n\r\n';
            let buf = Buffer.concat(chunks);
            let delimiter_index = buf.indexOf(delimiter);
            let end_index = buf.indexOf('\r\n' + head);
            let begin_index = 0;

            while (delimiter_index > 0) {//found multi-part

                let filename = get_part(buf.toString('utf8', begin_index, delimiter_index), 'filename="', '"');
                end_index = buf.indexOf('\r\n' + head, begin_index);

                if (filename && end_index > 0) {
                    save_file(filepath, filename, buf.subarray(delimiter_index + delimiter.length, end_index),
                        (err, msg) => {
                            res.end(msg);
                        }
                    )

                }
                if (end_index < 0) {
                    break;
                }


                begin_index = end_index + head.length;
                delimiter_index = buf.indexOf(delimiter, end_index);
            }

        } catch (er) {
            // uh oh! bad json!
            console.log(er)
            res.statusCode = 400;

            return res.end();
        }
    });



}

app.on("request", (req, res) => {

    //get
    if (req.method == 'GET') {
        http_get(req, res);
    } else if (req.method == 'POST') {
        http_post(req, res);
    } else {
        res.end();
    }
});


app.listen(port, () => {
    console.log(`Server running at ${port}`);
});