解决html2canvas 底部白边问题

html2canvas(document.getElementById("poster-canvas-box"), {
  useCORS: true,
  height: document.getElementById("poster-canvas-box").clientHeight - 2,
 // canvas高度与所截图高度相同或者更小，解决底部白边问题
  width: document.getElementById("poster-canvas-box").clientWidth - 2}).then((canvasElement) => {
  // do something
})