问两个javascript参数如何传递"this“

EN

<button type="button" aria-haspopup="dialog" aria-controls="a" onclick="openLayer($('#a'))"> button</button>

<div role="dialog" id="a"><"button type="button">close<"/button></div>

function openLayer(target){
    event.preventDefault();
    var backFocus = $("[aria-controls='"+target+"']");
    $(target).attr("tabindex", 0).attr("aria-hidden", false).show().focus();
    $(document).keyup(function(e){
        if (e.keyCode == "27"){
            console.log(backFocus); // [obeject object]
            $(target).attr("tabindex", 1).attr("aria-hidden", true).hide().blur();
        }
    });
}