js下载上传文件

function downloadFile(data, filename, mimeType) {
    const blob = new Blob([data], { type: mimeType });
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = filename;
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    URL.revokeObjectURL(url);
}

// 使用示例
const content = "Hello, world!";
downloadFile(content, "hello.txt", "text/plain");

<input type="file" id="fileInput" />
<button onclick="uploadFile()">Upload</button>

<script>
async function uploadFile() {
    const input = document.getElementById('fileInput');
    const file = input.files[0];
    if (!file) {
        alert('Please select a file.');
        return;
    }

    const formData = new FormData();
    formData.append('file', file);

    try {
        const response = await fetch('/upload', {
            method: 'POST',
            body: formData
        });

        if (response.ok) {
            alert('File uploaded successfully.');
        } else {
            alert('File upload failed.');
        }
    } catch (error) {
        console.error('Error uploading file:', error);
    }
}
</script>