a 标签

<a href="xxx.txt" download>下载</a>

动态创建a标签下载

function downloadUsingAnchorElement() {
  const anchor = document.createElement('a');
  anchor.href = IMG_URL;
  anchor.download = FILE_NAME;

  document.body.appendChild(anchor);
  anchor.click();
  document.body.removeChild(anchor);
}

fetch下载

function downloadFile(url, fileName) {
    fetch(url, {
        method: "get",
        mode: "no-cors",
        referrerPolicy: "no-referrer",
    })
        .then((res) => res.blob())
        .then((res) => {
            const aElement = document.createElement("a");
            aElement.setAttribute("download", fileName);
            const href = URL.createObjectURL(res);
            aElement.href = href;
            aElement.setAttribute("target", "_blank");
            aElement.click();
            URL.revokeObjectURL(href);
        });
}

XMLHttpRequest

let xhr = new XMLHttpRequest();
xhr.open('GET', 'http://www.xxx.com/bbb.zip', true);
// 这部至关重要，命令xhr返回给你的时blob(二进制大对象)类型的数据
xhr.responseType = 'blob';
xhr.send()
xhr.onreadystatechange = function () {
  if (xhr.readyState === 4 && xhr.status === 200) {
        const aTag = document.createElement('a')
        aTag.href = URL.createObjectURL(this.response)
        aTag.download = 'aaa.zip'
        aTag.click()
  }
}