js实现html网页直接转pdf

<script type="text/javascript" src="./js/html2canvas.js"></script>
<script type="text/javascript" src="./js/jsPdf.debug.js"></script>
<script type="text/javascript">
      var downPdf = document.getElementById("renderPdf");

      downPdf.onclick = function() {
          html2canvas(document.body, {
              onrendered:function(canvas) {

                  var contentWidth = canvas.width;
                  var contentHeight = canvas.height;

                  //一页pdf显示html页面生成的canvas高度;
                  var pageHeight = contentWidth / 592.28 * 841.89;
                  //未生成pdf的html页面高度
                  var leftHeight = contentHeight;
                  //pdf页面偏移
                  var position = 0;
                  //a4纸的尺寸[595.28,841.89]，html页面生成的canvas在pdf中图片的宽高
                  var imgWidth = 595.28;
                  var imgHeight = 592.28/contentWidth * contentHeight;

                  var pageData = canvas.toDataURL('image/jpeg', 1.0);

                  var pdf = new jsPDF('', 'pt', 'a4');

                  //有两个高度需要区分，一个是html页面的实际高度，和生成pdf的页面高度(841.89)
                  //当内容未超过pdf一页显示的范围，无需分页
                  if (leftHeight < pageHeight) {
                      pdf.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight );
                  } else {
                      while(leftHeight > 0) {
                          pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
                          leftHeight -= pageHeight;
                          position -= 841.89;
                          //避免添加空白页
                          if(leftHeight > 0) {
                              pdf.addPage();
                          }
                      }
                  }

                  pdf.save('content.pdf');
              }
          })
      }
    </script>

需要引入html2canvas.js和jsPdf.debug.js，触发点击事件，直接把该页面html转pdf