d3-to-png.js

const svg = document.querySelectorAll('#chart svg')[0]

const width = svg.getAttribute("width")
const height = svg.getAttribute("height")

const image = new Image()
image.setAttribute("width", width)
image.setAttribute("height", height)

const clone = svg.cloneNode(true)

const style = document.createElement('style')
style.innerHTML = `
  .d3-flame-graph rect {
    stroke: #EEEEEE;
    fill-opacity: .8;
  }
  
  .d3-flame-graph rect:hover {
    stroke: #474747;
    stroke-width: 0.5;
    cursor: pointer;
  }
  
  .d3-flame-graph-label {
    pointer-events: none;
    white-space: nowrap;
    text-overflow: ellipsis;
    overflow: hidden;
    font-size: 12px;
    font-family: Verdana;
    margin-left: 4px;
    margin-right: 4px;
    line-height: 1.5;
    padding: 0 0 0;
    font-weight: 400;
    color: black;
    text-align: left;
  }`
clone.appendChild(style)
 
const xml = new XMLSerializer().serializeToString(clone);
image.src = 'data:image/svg+xml;base64,' + btoa(xml)
// image.onload = console.log("image loaded")
image.onload = () => {
    console.log('image loaded')
    const canvas = document.createElement('canvas')
    canvas.setAttribute("width", width)
    canvas.setAttribute("height", height)

    canvas.getContext('2d').drawImage(image, 0, 0)

    const win = window.open(canvas.toDataURL("image/png"),'flamegraph')
}