function merger(imgs,maxWidth){	if(!imgs) 		return null;		maxWidth = maxWidth || 500;		var height = 0;	for (var i = 0; i < imgs.length; i++) {		var img = imgs[i];		if (img.width > maxWidth) {			height += img.height * (maxWidth / img.width);			continue;		}		height += img.height;	}		var canvas = document.createElement("canvas");	canvas.width = maxWidth+10;	canvas.height = height+10;	var ctx = canvas.getContext("2d");		var dheight = 10;	for (var i = 0; i < imgs.length; i++) {		var img = imgs[i];		var cheight = img.height;		var cwidth = img.width;		if (cwidth > maxWidth) {			cwidth = maxWidth;			cheight = img.height * (maxWidth / img.width);		}				ctx.drawImage(img, 10, dheight, cwidth, cheight);		dheight += cheight;	}			var dataurl = canvas.toDataURL('image/png');	return dataurl;}