你不需要提醒那个值，你需要传递它.当前您正在传递字符串 title.

You don't need to alert that value, you need to pass it. Currently you are passing the string title.

    $.ajax({
        url: "/useradminpage?main_id=%s&display=false",
        data: {main_id: this.attr("title")}
        success: function(data) {
        display_false()
        alert(4 - "returned");
        }
    });