The dygraphs library relies heavily on the HTML5 <canvas> tag, which Microsoft Internet Explorer did not traditionally support. To use Microsoft's native canvas implementation in IE9, you need to set an HTML5 doctype on your page:
<!DOCTYPE html>
When IE9 is in HTML5 mode, dygraphs works just like in other modern browsers.
If you need to support older versions of IE, which do not have native
<canvas> implementations, you'll need to use the 1.x series of dygraphs and follow its instructions for IE.