方法一（支持Chrome和Firefox）：

  1. function downloadTxt(filename, text) {
  2.     const pom = document.createElement('a');
  3.     pom.setAttribute('href', 'data:text/plain;charset=utf-8,' + encodeURIComponent(text));
  4.     pom.setAttribute('download', filename);
  5.     if (document.createEvent) {
  6.         const event = document.createEvent('MouseEvents');
  7.         event.initEvent('click', true, true);
  8.         pom.dispatchEvent(event);
  9.     } else {
  10.         pom.click();
  11.     }
  12. }

方法二（支持Chrome）：

  1. function downloadTxt(filename, content, contentType) {
  2.     if (!contentType) contentType = 'application/octet-stream';
  3.     const a = document.createElement('a');
  4.     const blob = new Blob([content], {'type': contentType});
  5.     a.href = window.URL.createObjectURL(blob);
  6.     a.download = filename;
  7.     a.click();
  8. }

来源：https://www.jianshu.com/p/40cfe9a12f9e