JSFiddle - React, Tailwind, and code Playground

HTML

<button id="btn">下载</button>
<a id="downloadCsv"></a>

JavaScript

const btn = document.getElementById('btn');
btn.addEventListener('click', function () {
    let headers = ['时段', '2018-08-01', '2018-08-01', '2018-08-01'];
    let dataSource = [
        ['00时', 345, 65, 8],
        ['06时', 23, 56, 89],
        ['12时', 21, 4, 7],
        ['18时', 67, 9, 34],
    ];
    let csv = '\uFEFF';
    csv += headers.join(',') + '\r\n';
    dataSource.forEach( (record) => {
        csv += (record.join(',') + '\r\n');
    });
    const blob = new window.Blob([csv], { type: 'text/csv,charset=UTF-8' });
    const downloadCsv = document.getElementById('downloadCsv');
    downloadCsv.href = window.URL.createObjectURL(blob);
    downloadCsv.click();
    window.URL.revokeObjectURL(blob);
})