使用Javascript下载HTTP文件

fetch('http://example.com/file.txt')
  .then(response => response.blob())
  .then(blob => {
    const url = window.URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = 'file.txt';
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
  })
  .catch(error => console.error(error));

const xhr = new XMLHttpRequest();
xhr.open('GET', 'http://example.com/file.txt', true);
xhr.responseType = 'blob';
xhr.onload = function() {
  if (this.status === 200) {
    const blob = this.response;
    const url = window.URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = 'file.txt';
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
  }
};
xhr.send();