You can easily embed HTML in both the header and body:
var notification = new Notification('<title>title</title>',{body:'<b>bold</b> content'});
But it makes no sense: it will not render. In Firefox, it will look like this:

spec says that each of them is just a DOMString , which means plain text.
If you only care about Chrome support, you can take a look at Rich Notifications . Otherwise, it seems that we need to wait until some means for creating notifications on the desktop appear.
dakab
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