Nodejs如何把接收图片base64格式保存为文件存储到服务器上

app.post('/upload', function(req, res){
//接收前台post过来的base64
var imgdata = req.body.imgdata;
//过滤data:url
var base64data = imgdata.replace(/^data:image\/\w+;base64,/, "");
var databuffer = new buffer(base64data, 'base64');
fs.writefile("image.png", databuffer, function(err) {
if(err){
res.send(err);
}else{
res.send("保存成功！");
}
});
});