Are single/double quotes allowed inside HTML attribute values?

I'm trying to set attribute value that contains a single quote:

var attr_value = "It's not working";
var html = "<label my_attr='" + attr_value + "'>Text</label>";
$('body').html(html);

However, I get the following result:

<label working="" not="" s="" my_attr="It">Text</label>

How could I fix this ?

Are double quotes allowed inside attribute values ?