前端JavaScript根据文件url下载到本地多种方法实现

function downloadByATag(url, filename) {
  const a = document.createElement('a');
  a.href = url;
  a.download = filename || 'default-name'; // 设置下载文件名
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
}

async function fetchAndDownload(url, filename) {
  try {
    const response = await fetch(url);
    const blob = await response.blob();
    const downloadUrl = URL.createObjectURL(blob);
    
    const a = document.createElement('a');
    a.href = downloadUrl;
    a.download = filename || 'file';
    a.click();
    
    URL.revokeObjectURL(downloadUrl); // 释放内存
  } catch (error) {
    console.error('下载失败:', error);
  }
}

function downloadByForm(url) {
  const form = document.createElement('form');
  form.method = 'GET';
  form.action = url;
  document.body.appendChild(form);
  form.submit();
  document.body.removeChild(form);
}

// 综合方案（推荐）
async function downloadFile(url, filename) {
  if (url.startsWith('http') && !url.startsWith(window.location.origin)) {
    // 跨域文件使用 Fetch
    await fetchAndDownload(url, filename);
  } else {
    // 同源文件直接下载
    downloadByATag(url, filename);
  }
}