使用javascript / API实现跨平台PDF下载的方法

function downloadPDF(url) {
  var link = document.createElement('a');
  link.href = url;
  link.download = 'file.pdf';
  link.target = '_blank';
  link.click();
}

var pdfUrl = 'https://example.com/file.pdf';
downloadPDF(pdfUrl);

<script src="https://cdnjs.cloudflare.com/ajax/libs/pdf.js/2.11.338/pdf.min.js"></script>

function downloadPDF(url) {
  var loadingTask = pdfjsLib.getDocument(url);
  loadingTask.promise.then(function(pdf) {
    pdf.getPage(1).then(function(page) {
      var viewport = page.getViewport({ scale: 1.0 });
      var canvas = document.createElement('canvas');
      var context = canvas.getContext('2d');
      canvas.height = viewport.height;
      canvas.width = viewport.width;

      var renderContext = {
        canvasContext: context,
        viewport: viewport
      };

      page.render(renderContext).promise.then(function() {
        canvas.toBlob(function(blob) {
          var link = document.createElement('a');
          link.href = URL.createObjectURL(blob);
          link.download = 'file.pdf';
          link.target = '_blank';
          link.click();
        }, 'application/pdf');
      });
    });
  });
}

var pdfUrl = 'https://example.com/file.pdf';
downloadPDF(pdfUrl);