将javascript呈现的svg图像保存为本地磁盘为.png文件

I am new to SVG and not an advanced user of JavaScript. I have a webpage with svg content dynamically rendered by javascript. In Internet Explorer when I right click on the svg content, I get option "Save Picture As" and I am able to save the content as png or svg.I am new to SVG and not an advanced user of Jav