如何使用jQuery检测页面的滚动位置

Question

I am having trouble with jQuery functionality on my website. What it does, is that it uses the window.scroll() function to recognize when the windows changes its scroll position and at the change calls a few functions to load data from the server.

The problem is the .scroll() function is called as soon as there is even a little change in the scroll position and loads data at the bottom; however, what I wish to achieve is to load new data when the scroll/page position reaches at the bottom, like it happens for Facebook feed.

But I am not sure how to detect scroll position using jQuery?

function getData() {
  $.getJSON('Get/GetData?no=1', function (responseText) {
    //Load some data from the server
  })
};

$(window).scroll(function () {
    getData();
});

Answer 1

You can extract the scroll position using jQuery's .scrollTop() method

$(window).scroll(function (event) {
    var scroll = $(window).scrollTop();
    // Do something
});

Answer 2

You are looking for the window.scrollTop() function.

$(window).scroll(function() {
    var height = $(window).scrollTop();

    if(height  > some_number) {
        // do something
    }
});

Answer 3

Check here DEMO http://jsfiddle.net/yeyene/Uhm2J/

function getData() {
    $.getJSON('Get/GetData?no=1', function (responseText) {
        //Load some data from the server
    })
};

$(window).scroll(function() {
   if($(window).scrollTop() + $(window).height() == $(document).height()) {
       alert("bottom!");
       // getData();
   }
});

Answer 4

$(window).scroll( function() { 
 var scrolled_val = $(document).scrollTop().valueOf();
 alert(scrolled_val+ ' = scroll value');
});

This is another way of getting the value of scroll.

Answer 5

Now that works for me...

$(document).ready(function(){

    $(window).resize(function(e){
        console.log(e);                   
    });

    $(window).scroll(function (event) {
        var sc = $(window).scrollTop();
        console.log(sc);
    });

})

it works well... and then you can use JQuery/TweenMax to track elements and control them.

Answer 6

Store the value of the scroll as changes in HiddenField when around the PostBack retrieves the value and adds the scroll.

//jQuery

jQuery(document).ready(function () {

    $(window).scrollTop($("#<%=hidScroll.ClientID %>").val());

    $(window).scroll(function (event) {
        $("#<%=hidScroll.ClientID %>").val($(window).scrollTop());
    });
});

var prm = Sys.WebForms.PageRequestManager.getInstance();

prm.add_endRequest(function () {

    $(window).scrollTop($("#<%=hidScroll.ClientID %>").val());

    $(window).scroll(function (event) {
        $("#<%=hidScroll.ClientID %>").val($(window).scrollTop());
    });
});

//Page Asp.Net
<asp:HiddenField ID="hidScroll" runat="server" Value="0" />

Answer 7

You can add all pages with this code:

JS code:

 /* Top btn */
    $(window).scroll(function() {
        if ($(this).scrollTop()) {
            $('#toTop').fadeIn();
        } else {
            $('#toTop').fadeOut();
        }
    });
    var top_btn_html="<topbtn id='toTop' onclick='gotoTop()'>&#8593;</topbtn>";
    $('document').ready(function(){
        $("body").append(top_btn_html);
    });
    function gotoTop(){
        $("html, body").animate({scrollTop: 0}, 500);    
    }
    /* Top btn */

CSS CODE

/*Scrool top btn*/
#toTop{
    position: fixed;
    z-index: 10000;
    opacity: 0.5;
    right: 5px;
    bottom: 10px;
    background-color: #ccc;
    border: 1px solid black;
    width: 40px;
    height: 40px;
    border-radius: 20px;
    color: black;
    font-size: 22px;
    font-weight: bolder;
    text-align: center;
    vertical-align: middle;
}

Answer 8

$('.div').scroll(function (event) {
 event.preventDefault()
 var scroll = $(this).scrollTop();
 if(scroll == 0){
   alert(123)
 }
});

This code for chat_boxes for loading previous messages

Answer 9

GET Scroll Position:

var scrolled_val = window.scrollY;

DETECT Scroll Position:

$(window).scroll
(
     function (event) 
     {
          var scrolled_val = window.scrollY;
          alert(scrolled_val);
     }
 );