jQuery .search() to any string

I saw this code snippet:

$("ul li").text().search(new RegExp("sometext", "i"));

and wanted to know if this can be extended to any string?

I want to accomplish the following, but it dosen't work:

$("li").attr("title").search(new RegExp("sometext", "i"));

Also, anyone have a link to the jQuery documentation for this function? I fail at googling apparently.