canvas 이미지 다운로드

<a id="download">
    <button type="button" onClick="download()">Download</button>
</a>
    
<canvas id="myCanvas" width="720" height="450">
    Your browser does not support Canvas.
</canvas>

function download() {
    var download = document.getElementById("download");
    var image = document.getElementById("myCanvas")
        .toDataURL("image/png")
        .replace("image/png", "image/octet-stream");
    download.setAttribute("href", image);
    download.setAttribute("download","image-name.png");
}