How is jquery used to check for the 'disabled' attribute on an <a> tag?

I have a disabled='disabled' attribute on an <a> tag. How do I test to see if this attribute is on my tag using jquery? The following code returns undefined. I can see the disabled attribute on the tag in firebug and all other attributes on the anchor return successfully using the same syntax. I realize disabled is a custom attribute for an <a> tag.

$('#anchorID').attr('disabled');