jQuery中止ajax请求

I have a function that is called when scroll reaches the bottom of my div element.

$(document).ready(function(){

$("#container").scroll(function() {
        var current_scrollbar_position = Math.round($(this).scrollTop());
        var inner_height = Math.round($(this).innerHeight());
        var advertiser_dropdown_height = $(this)[0].scrollHeight;
        var dropdown_bottom = current_scrollbar_position + inner_height;

        if(dropdown_bottom >= Math.round(0.75*(advertiser_dropdown_height)))
        {
           load_advertisers();                        
        }
    });
});

function load_advertisers(){
        // calling ajax function
}

When scroll reaches the end, it calls load_advertisers() method. But it calls load_advertisers() more than once. As a result, it aborts any other request, and only fetches data from one request. So, if we inspect the console, it shows 5-6 aborted ajax requests (in red). Why does it happen? How can I prevent another request if the previous request is processing?

Any help is appreciated.

Thanks.