js 刷新當前頁面會彈出提示框怎樣將這個提示框去掉

//禁止刷新提示
window.onbeforeunload = function() {
    var n = window.event.screenX - window.screenLeft;
    var b = n > document.documentElement.scrollWidth-20;
    if(b && window.event.clientY < 0 || window.event.altKey){

    }else{
        location.href=location.href;  //當前頁面等於當前頁面
    }
}