download JMdict_e.gz with node.js

JMdict_e.js

const http = require('http');
const url = require('url');
const path = require('path');
const fs = require('fs');

function wget(source, { onStart, onProgress } = {}) {
    return new Promise(function(y, n) {
        const output = path.basename(url.parse(source).pathname);

        const req = http.request(source,
            function(res) {
                if (res.statusCode === 200) {
                    const fileSize = Number.isInteger(res.headers['content-length'] - 0) ?
                        parseInt(res.headers['content-length']) :
                        0;
                    let downloadedSize = 0;

                    /**
                     * Create write stream
                     */
                    var writeStream = fs.createWriteStream(output, {
                        flags: 'w+',
                        encoding: 'binary'
                    });

                    res.pipe(writeStream);

                    if (onStart) {
                        onStart(res.headers);
                    }

                    res.on('data', function(chunk) {
                        downloadedSize += chunk.length;
                        if (onProgress) {
                            onProgress({
                                fileSize,
                                downloadedSize,
                                percentage: fileSize > 0 ? downloadedSize / fileSize : 0
                            });
                        }
                    });

                    res.on('error', function(err) {
                        writeStream.end();
                        n(err);
                    });

                    writeStream.on('finish', function() {
                        writeStream.end();
                        req.end('finished');
                        y({ headers: res.headers, fileSize });
                    });
                } else {
                    n('Server responded with unhandled status: ' + res.statusCode);
                }
            }
        );

        req.end('done');
        req.on('error', err => n(err));
    });
}



wget('http://ftp.monash.edu.au/pub/nihongo/JMdict_e.gz', {
        onStart: headers => {
            console.log(headers['content-type']);
        },
        onProgress: progress => {
            console.log('downloaded', progress.percentage * 100, '%');
        }
    })
    .then(result => {
        //done();
    })
    .catch(err => {
        console.log(err);
    });