将d3heatmap的图像保存在文件中

I am using d3heatmap package in R for to draw heatmaps. When I use it in Rstudio, I can save images that it produces by choosing save image from the viewer menu. I am wondering how I can save the heatmap to a file in an Rscript. Apparently, png(filename) does not work.I am using d3heatmap package in R for to draw h