Javascript NodeJS:WriteStream close事件在承诺被拒绝后运行

我使用以下代码从网站下载图像。有时，如果出现错误，网站将返回HTML页面而不是图像。为了避免下载HTML页面而不是图像，当我收到响应头时，如果内容类型是HTML，我拒绝下载功能。当我在响应事件中拒绝我的函数时，我的拒绝在下载函数之外成功处理。但是，下载函数即使在被拒绝后仍将继续运行（就好像返回被忽略一样），最终将在writeStream的end事件中运行代码

如何阻止下载功能在被拒绝后继续运行

const fs = require('fs-extra');
const request = require('request');
var probe = require('probe-image-size');
var progress = require('request-progress');

var filename = 'C:/Users/User/Desktop/myimage.jpg';
var writeSteam = fs.createWriteStream(filename)
var req = request(createRequestHeaders('www.linktomyimage.com/image.jpg'));

downloadImage(req, filename).then((fileInfo) => {
    console.log('Successfully downloaded.');
}).catch((error) => {
    console.log('Handle rejections and do something else.');
});

function createRequestHeaders(url) {
    var cookie = `userid=${userid}; phash=${phash};`;
    return {
        'url': url,
        'method': 'GET',
        'gzip': true,
        'headers': {
            'Referer': `https://${website}/`,
            'Cookie': cookie
        }
    };
}

function downloadImage(req, filename) {
    return new Promise((resolve, reject) => {
        var response = null;
        var bytes;
        var dirname = path.dirname(filename);
        if (!fs.existsSync(dirname)) fs.ensureDirSync(dirname);

        progress(req, { delay: 0 }).on('progress', function (state) {
            updateDownloadSpeed(state.speed);
        }).on('end', function () {
            writeSteam.on('close', () => {
                if (bytes !== writeSteam.bytesWritten) {
                    // Here the write stream is closed, so we can compare the property bytesWritten with the bytes we expected to receive
                    console.log('The size is not equal! Image is corrupt!')
                    reject({ 'name': 'ImageCorrupt' });
                    return;
                } else if (response.statusCode === 200) {
                    var input = require('fs').createReadStream(filename);
                    probe(input).then(result => {
                        input.destroy();
                        if (result != null) {
                            resolve({
                                bytes: bytes, width: result.width,
                                height: result.height,
                            });
                        } else {
                            reject({ 'name': 'ImageMissingOrCorrupt' });
                            return;
                        }
                    }).catch((error) => {
                        reject(error);
                        return;
                    });
                } else {
                    // This is never triggered when the download stops and the image is truncated
                    reject({ 'name': 'StatusCodeError', 'message': response.statusCode });
                    return;
                }
            });
        }).on('response', function (resp) {
            response = resp;
            if (mime.getExtension(response.headers['content-type']) == 'html') {
                // Even if this is triggered and the Promise rejects, the code under the writeStream's close event still triggers
                reject({ 'name': 'RecievedHTML' });
                return;
            } else {
                // Get the expected size of the file so we can test if it is entirely downloaded later
                bytes = parseInt(response.headers['content-length']);
            }
        }).on('error', function (error) {
            reject(error);
            return;
        }).pipe(writeSteam);
    });
}

---

因为您在没有任何条件的情况下调用

管道

从底部卸下

管道（writeStream）

，并将其放置在

else

块中：

if（mime.getExtension（response.headers['content-type']）=='html'）{
//即使这被触发并且承诺被拒绝，writeStream的close事件下的代码仍然会触发
拒绝（{'name'：'receivedhtml'}）；
返回；
}否则{
//获取文件的预期大小，以便我们可以测试它是否在以后完全下载
bytes=parseInt（response.headers['content-length']）；
此.pipe（writeStream）；
}

如果出现问题并触发请求的错误事件，该怎么办？writeStream end事件还会触发吗？我认为如果在请求过程中发生错误，那么根本不会发出

响应
事件，因此
writeStream
甚至不会启动。