download div element as image via DevTools.

devtool-image-downloader.js

// 1. create script element and append to head;
const sc = document.createElement("script");
sc.setAttribute("src", "https://cdnjs.cloudflare.com/ajax/libs/html2canvas/0.4.1/html2canvas.min.js");
document.head.append(sc)

// 2.create downloader function
function downloadBase64File(contentType, base64Data, fileName) {
  const linkSource = `data:${contentType};base64,${base64Data}`;
  const downloadLink = document.createElement("a");
  downloadLink.href = linkSource;
  downloadLink.download = fileName;
  downloadLink.click();
}

// 3.executed as an IIFE. (needs an target id as param)
(function getScreenShot(id){
    let c = document.getElementById(id);
    let h = html2canvas(c, {
    onrendered: function(canvas) {
      let t = canvas.toDataURL().replace("data:image/png;base64,", "");
      downloadBase64File('image/png',t,'image');
    }
})}
)("div_print");