SVG to PNG

svg2png.js

var svg = document.querySelector( "svg" );
var svgData = new XMLSerializer().serializeToString( svg );

var canvas = document.createElement( "canvas" );
var ctx = canvas.getContext( "2d" );

var img = document.createElement( "img" );
img.setAttribute( "src", "data:image/svg+xml;base64," + btoa( svgData ) );

img.onload = function() {
    ctx.drawImage( img, 0, 0 );
    
    // Now is done
    console.log( canvas.toDataURL( "image/png" ) );
};

if the svg element contains some tag, these code seems not work

sorry can somebody tell me what is container hier ? image Tag?
function svg_to_png(container) {
var wrapper = document.getElementById(container);
var svg = wrapper.querySelector("svg");

if (typeof window.XMLSerializer != "undefined") {
    var svgData = (new XMLSerializer()).serializeToString(svg);
} else if (typeof svg.xml != "undefined") {
    var svgData = svg.xml;
}

var canvas = document.createElement("canvas");
var svgSize = svg.getBoundingClientRect();
canvas.width = svgSize.width;
canvas.height = svgSize.height;
var ctx = canvas.getContext("2d");

var img = document.createElement("img");
img.setAttribute("src", "data:image/svg+xml;base64," + btoa(unescape(encodeURIComponent(svgData))) );

img.onload = function() {
    ctx.drawImage(img, 0, 0);
    var imgsrc = canvas.toDataURL("image/png");

    var a = document.createElement("a");
    a.download = container+".png";
    a.href = imgsrc;
    a.click();
};

}