How does jquery pass and assign the element where the current mouseover is located to its internal function?

var handle = null;
$("#div_menu_1_con a").mouseover(function () { 
handle = setTimeout(changethis(？？？), 3000);
}).mouseout(function () {
clearTimeout(handle);
});
function changethis(selector){。。。。。。}；

$("#元素id").mouseover(function(){
    //将mouseover所在元素传递赋值给其所在内部函数，就是将元素本身传递给内部函数
    //jQuery中元素绑定函数内$(this)就可以获取到当前元素
    //所以,如下调用
     
    show($(this));//$(this)将当前元素当作参数传递过去
     
});
function show(obj){
    alert(obj.text());
}

$("#div_menu_1_con a").mouseover(function () {
var activeElement=this;
handle = setTimeout(function(){
changethis(activeElement);
}, 3000);
}).mouseout(function () {
clearTimeout(handle);
});
function changethis(selector){。。。。。。}；