You should use it this way:
$('body').html2canvas();
var queue = html2canvas.Parse();
var canvas = html2canvas.Renderer(queue,{elements:{length:1}});
var img = canvas.toDataURL();
window.open(img);
It took me few hours to figure it out, how to use it the right way.
The {elements:{length:1}}
is required, due to incomplete implementation of the plugin, otherwise you’ll get an error.
Good luck!