实现代码

/* eslint-disable */
// 不使用JQuery版的
import html2canvas from 'html2canvas'
// 下载
function downloadPDF (num, count, pdf, colorWidth, colorNum, title) {
  window.scrollTo(0, 0)
  let ele = document.querySelector('#id_' + num)
  let objWidth = count === 0 ? 100 : (parseInt((num / count) * 100) > 100 ? 100 : parseInt((num / count) * 100))
  colorWidth.style.width = objWidth + '%'
  colorNum.innerText = objWidth
  let eleW = ele.offsetWidth // 获得该容器的宽
  let eleH = ele.offsetHeight // 获得该容器的高
  let eleOffsetTop = ele.offsetTop  // 获得该容器到文档顶部的距离
  let eleOffsetLeft = ele.offsetLeft  // 获得该容器到文档最左的距离
  var canvas = document.createElement('canvas')
  var abs = 0
  let win_in = document.documentElement.clientWidth || document.body.clientWidth // 获得当前可视窗口的宽度（不包含滚动条）
  let win_out = window.innerWidth // 获得当前窗口的宽度（包含滚动条）
  if (win_out > win_in) {
    abs = (win_out - win_in) / 2    // 获得滚动条宽度的一半
  }
  canvas.width = eleW * 2    // 将画布宽&&高放大两倍
  canvas.height = eleH * 2
  var context = canvas.getContext('2d')
  context.scale(2, 2)
  context.translate(-eleOffsetLeft - abs, -eleOffsetTop)
  // 这里默认横向没有滚动条的情况，因为offset.left(),有无滚动条的时候存在差值，因此
  // translate的时候，要把这个差值去掉
  html2canvas(ele, {
    async: false,
    dpi: 300,
    scale: 2,    //设置缩放
    // allowTaint: true,  //允许 canvas 污染， allowTaint参数要去掉，否则是无法通过toDataURL导出canvas数据的
    useCORS: true  //允许canvas画布内 可以跨域请求外部链接图片, 允许跨域请求。
  }).then((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;
    //一页pdf显示html页面生成的canvas高度;
    if (eleW < eleH) {
      pageHeight = contentWidth / 595.28 * 841.89
    } else {
      pageHeight = contentWidth / 841.89 * 595.28
    }
    //未生成pdf的html页面高度
    var leftHeight = contentHeight
    //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, imgHeight
    if (eleW < eleH) {
      imgWidth = 595.28;
      imgHeight = 595.28/contentWidth * contentHeight
    } else {
      imgWidth = 841.89
      imgHeight = 841.89/contentWidth * contentHeight
    }
    var pageData = canvas.toDataURL('_uploads/photos/jpeg', 1.0)
    if (leftHeight < pageHeight) {
      pdf.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight)
    } else {
      while (leftHeight > 10) {
        pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
        leftHeight -= pageHeight
        position -= 841.89
        //避免添加空白页
        if (leftHeight > 10) {
          pdf.addPage()
        }
      }
    }
    //可动态生成
    if (num === count) {
      pdf.save(title)
    } else {
      pdf.addPage()
      num++
      downloadPDF(num, count, pdf, colorWidth, colorNum, title)
    }
  })
}

export default {
  downloadPDF
}