Javascript 通过我的前端从node express服务器下载JSON文件

我已将文件上传到项目目录中的下载文件夹后存储。 我想从前端下载保存的文件。 当我点击下载按钮时，它不会获取文件

当我进入

http://localhost:5000/download

在express应用程序上，我收到了此错误消息

错误：发送邮件后无法设置邮件头。

Express服务器代码：

app.get('/download', (req, res) => {
    res.send('file downloaded')
    const file = './downloads/output.yml';
    res.download(file, 'openapi.yml', (err) => {
        if (err) {
            console.log(err)
        } else {
            console.log('file downloaded')
        }
    });
});

<button class="download-btn">download</button>

const handleDownload = async () => {
    const res = await fetch("https://cors-anywhere.herokuapp.com/http://localhost:5000/download");
    const blob = await res.blob();
    download(blob, 'output.yml');
}

downloadBtn.addEventListener('click', handleDownload);

前端应用程序代码：

app.get('/download', (req, res) => {
    res.send('file downloaded')
    const file = './downloads/output.yml';
    res.download(file, 'openapi.yml', (err) => {
        if (err) {
            console.log(err)
        } else {
            console.log('file downloaded')
        }
    });
});

<button class="download-btn">download</button>

const handleDownload = async () => {
    const res = await fetch("https://cors-anywhere.herokuapp.com/http://localhost:5000/download");
    const blob = await res.blob();
    download(blob, 'output.yml');
}

downloadBtn.addEventListener('click', handleDownload);

HTML:

app.get('/download', (req, res) => {
    res.send('file downloaded')
    const file = './downloads/output.yml';
    res.download(file, 'openapi.yml', (err) => {
        if (err) {
            console.log(err)
        } else {
            console.log('file downloaded')
        }
    });
});

<button class="download-btn">download</button>

const handleDownload = async () => {
    const res = await fetch("https://cors-anywhere.herokuapp.com/http://localhost:5000/download");
    const blob = await res.blob();
    download(blob, 'output.yml');
}

downloadBtn.addEventListener('click', handleDownload);

文件夹结构：

app.get('/download', (req, res) => {
    res.send('file downloaded')
    const file = './downloads/output.yml';
    res.download(file, 'openapi.yml', (err) => {
        if (err) {
            console.log(err)
        } else {
            console.log('file downloaded')
        }
    });
});

<button class="download-btn">download</button>

const handleDownload = async () => {
    const res = await fetch("https://cors-anywhere.herokuapp.com/http://localhost:5000/download");
    const blob = await res.blob();
    download(blob, 'output.yml');
}

downloadBtn.addEventListener('click', handleDownload);

更新： Server.js

const uploadFiles = async (req, res) => {
    const file = await req.files[0];
    console.log(file)
    postmanCollection = file.path;
    outputFile = `downloads/${file.filename}.yml`
    convertCollection();
    res.json({ message: "Successfully uploaded files" });
}

app.post("/upload_files", upload.array("files"), uploadFiles);

---

任何人请帮我解决这个问题。

您已经在使用

res.send

，它会将响应头发送回客户端，从而结束请求-响应周期，当您尝试执行

res.download

时，它会抛出错误。改用

 app.get('/download', (req, res) => {
      const file = './downloads/output.yml';
        res.download(file, 'openapi.yml', (err) => {
            if (err) {
                console.log(err)
            } else {
                console.log('file downloaded')
            }
        });
    });

res.send（'file downloaded'）

-->删除此行

您还需要更新js代码

const handleDownload = async () => {
    const res = await fetch("https://cors-anywhere.herokuapp.com/download"); //http://localhost:5000--->this is not required
    const blob = await res.blob();
    download(blob, 'output.yml');
}

downloadBtn.addEventListener('click', handleDownload);

---

你好，谢谢你的帮助，现在我可以下载文件时，我点击这个。但是，当我点击前端的下载按钮时，它仍然会显示相同的错误消息并下载一个空文件脚本。js:24 GET 403（禁止）参见updates@RishiPurwarNow，它会在前端显示此错误消息“加载资源失败：服务器以403（禁止）的状态响应”后端上的此错误消息“node:19280）unhandledPromisejectionWarning:TypeError:无法读取未定义的“我看不到

path

问题中的任何地方请更新问题我更新问题，请检查