html2canvas(document.querySelector("#u2044_img")).then(canvas => {
var image= canvas.toDataURL("image/png").replace("image/png", "image/octet-stream");
console.log(image);
window.location.href=image;
<script src="html2canvas.js"></script>
<script>
function doCapture(){
html2canvas(document.querySelector('#pslideshowu1013')).then( canvas =>{
var img=canvas.toDataURL("image/png").replace("image/png","image/octet-stream");
console.log(img);
window.location.href=img;
});
}
</script>
<button onclick="doCapture();">222</button>