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How do I code JQuery so that when I scroll to a certain element, Nav bar appears at top, when I scroll back up past that element, nav bar disappears

I have a div called #menu which I want to display when I scroll past the element #section3, if I scroll up past that element again, I want #menu to disappear
How would I code this?

Maybe something like this?
scrolled = "no"
$(window).scroll(function(){
scr = $("body").scrollTop();
if (scr > 100 && scrolled == "no"){
$("#menu").css({"display:block"})
displayed = "yes"
}
if (displayed == "yes" && scrolled = "yes"){
$("#menu").css({"display:none"})
}
});
The above assumes that #section3 is 100 pixels down the page. If you do not know where its going to be on the page then you could use the method outlined here:
Trigger event when user scroll to specific element - with jQuery

With jQuery you can get the scroll position with $("body").scrollTop();.
Expanding on what #Ned Hulton said, I recommend comparing the scroll position to the top of a "container element" (or 'row') in your page like this:
if ($('body').scrollTop() > $('#someRow').offset().top){
//do something
}
That way you can account for your container appearing at a variable distance down the page (which will come in handy for mobile browsing or cases where your text wraps to additional lines)

I just whipped this up in jsfiddle
https://jsfiddle.net/rb56j0yu/
it uses jQuery, and checks the scroll position against the target div. Css sets the menu as position: fixed, and defaults to hidden.
$(window).scroll(function(){
var yPos = $("body").scrollTop();
var yCheck = $("#c3").position().top;
if (yPos > yCheck && !$("#menu").is(":visible"))
{
$("#menu").show();
}
if (yPos <= yCheck && $("#menu").is(":visible"))
{
$("#menu").hide();
}
});

First, get your #section3 top offset and height. Which will be used as the threshold whether #section3 is actually on the window screen.
var top = $('#section3').offset().top;
var bot = topOffset + $('#section3').height();
Then, detect it on your scroll event.
$(window).on('scroll', function () {
var scrollTop = $(window).scrollTop();
if (scrollTop >= top && scrollTop <= bot) {
// #section3 is within the screen.
$('#menu').show();
}
else {
// #section3 is out of screen.
$('#menu').hide();
}
});

This is a common use case, I wrote following code:
// what does "Auto Header" mean, goto https://www.yahoo.com/
// scroll down and you will see the purple part auto fixed to top,
// while when scroll up, it restores and does not be fixed.
// 1. multiple auto header elements handled
// 2. dynamically create/remove elements issue handled
// 3. no unnecessary dom operation, high performance
// usage: just add 'class="auto-header"' to any element you want to auto header
// suggest set each auto-header element specific width and height
// do not guarantee it works when resize or scroll left/right
$(document).ready(function() {
var rawTops = [],
rawLefts = [],
rawStyles = [],
$locations = [], // record next sibling so that element easily find where to restore
fixed = []; // mark whether this element is fixed
$(".auto-header").each(function() {
var $this = $(this),
offset = $this.offset();
rawTops.push(offset.top);
rawLefts.push(offset.left);
rawStyles.push($this.attr("style"));
$locations.push($this.siblings().eq($this.index()));
fixed.push(false);
});
$(window).on("scroll", function() {
$(".auto-header").each(function(i, e) {
if(!fixed[i] && $(window).scrollTop() > rawTops[i]) {
var $te = $(this).clone(true);
$(this).remove();
$locations[i].before($te);
$te.css({
"position": "fixed",
"top": 0,
"left": rawLefts[i],
"z-index": 100
});
fixed[i] = true;
} else if(fixed[i] && $(window).scrollTop() < rawTops[i]) {
$(this).removeAttr("style").attr("style", rawStyles[i]);
fixed[i] = false;
}
});
});
});

Toggle class when object visible in the viewport

I need a script which toggle a class when another class or section is visible in the viewport (during scrolling).
Here I have an script which works for precised distance from top, but can somebody help me to modify it for my needs?
$(window).scroll(function(){
if ($(this).scrollTop() > 50) {
$('#viewport').addClass('turn_on');
} else {
$('#viewport').removeClass('turn_on');
}
});

A couple of things. First the scroll event (as well as the resize event) fire multiple times. Traditionally, developers have used something called debouncing to limit the number of times a function fires. I've never got it to work correctly, so instead I check if a condition is met before continuing. You are basically doing this already.
var bool = false
$(window).on('scroll', function(){
if(!bool){
bool = true;
//fire the function and then turn bool back to false.
};
});
The next thing you need is to identify the element to add the class to. Let's say it has an id of foo.
var yOffset = $('#foo').offset().top;
From here, you'll need to compare the current vertical scroll position with that of the yOffset. You may also need to add the height of the element for when it scrolls out of frame.
var elHeight = $('#foo').height();
The element should be completely in frame with the $(window).scrollTop() equals the yOffset and out of frame when the $(window).scrollTop() is greater than yOffset + elHeight.
This is all assuming the element isn't in the frame to begin with. If it is, it will be trickier but it's a start.

Working fiddle
Try to add function that detect if element passed in argument is visible :
function isVisisble(elem){
return $(elem).offset().top - $(window).scrollTop() < $(elem).height() ;
}
$(window).scroll(function(){
if (isVisisble( $('your_element') ))
$('#viewport').addClass('turn_on');
} else {
$('#viewport').removeClass('turn_on');
}
});
Hope this helps.

Thx everyone for help.
Here I found the solution: LINK
And here is the modified script:
$(document).ready(function () {
var windowHeight = $(window).height(),
gridTop = windowHeight * 0.1,
gridBottom = windowHeight * 1;
$(window).on('scroll', function () {
$('.inner').each(function () {
var thisTop = $(this).offset().top - $(window).scrollTop();
if (thisTop > gridTop && (thisTop + $(this).height()) < gridBottom) {
$(this).addClass('on');
}
});
});
});

Is it possible to hide one div and show another div after scrolling 50% or more?

i have one section inside 2 DIV's where the div's name 1st div and 2nd div . By Default 2nd div will be hidden, after scrolling 50% or more 1st div will be hidden and 2nd div will be displayed. How do i do that?
I used:
var heightDivid = $(window).height() / 2;
$(window).on('scroll', function(e){
$('.sections-class').each(function(){
if(this.getBoundingClientRect().top <= heightDivid ){
$(this).removeClass('heightDivids') ;
}
else{
$(this).addClass('heightDivids') ;
}
})
})

Perhaps you can alter something along these lines to do what you're attempting to do.
Utilize jQuery's scrollTop to identify where you want the change to occur.
Set a limit for when you want to hide the one div and show the two div.
$(window).scroll(function() {
var height = $(window).scrollTop();
if(height > 10) {
$('.two').show();
$('.one').hide();
}
});
Example: http://jsfiddle.net/xv2m4qn6/
If you want the effect to reverse simply add a second conditional:
Example: http://jsfiddle.net/xv2m4qn6/1/

At Last I did :) and it's work for me .... Thank you all for your help :)
var shadowEdgePoint = $(window).height() / 2;
$(window).on('scroll', function(e){
$('.section-class').each(function(){
if(this.getBoundingClientRect().top <= shadowEdgePoint){
$('.two').show();
$('.one').hide();
}
else{
$('.two').hide();
$('.one').show();
}
})
});

Infinite Scroll in both directions

I've been working on a small website and I want it to be scrollable and looped both upwards and downwards.
I made a jsfiddle to show my problem. Currently I'm working with this method:
$(document).ready(function(){
$(window).scroll(function() {
if ( $(window).scrollTop() >= ($('body').height() - $(window).height()) ) {
$(window).scrollTop(1);
}
else if ( $(window).scrollTop() == 0 ) {
$(window).scrollTop($('body').height() - $(window).height() -1);
}
});
});
http://jsfiddle.net/2LDFA/
My problem is, that there is no transition, this method only works if the content at the top and bottom is exactly the same.
Any Ideas how I can add the same div to top and bottom every time the user reaches the end?

Here is a working fiddle: http://jsfiddle.net/2L23c/
And here is the javascript:
(function($){
$(document).ready(function(){
var html = $(".what").html();
var what = '<div class="what">'+html+'</div>';
$(window).scrollTop(1);
$(window).scroll(function() {
if ( $(window).scrollTop() >= ($('body').height() - $(window).height()) ) {
$(".what").last().after(what);
if ($(".what").length > 2) {
$(".what").last().prev().remove();
$(window).scrollTop($(window).scrollTop() - $(".what").first().height());
}
}
else if ( $(window).scrollTop() == 0 ) {
$(".what").first().before(what);
$(window).scrollTop($(".what").first().height());
if ($(".what").length > 2) {
$(".what").last().remove();
}
}
});
});
})( jQuery );

Well, if you're using jquery, you can move the divs around on the page fairly easily, using insertAfter or the like. When you get to the bottom, grab the first div on the page and move it down to right after the last one. There's some interesting and slightly finicky work to be done in making sure you always get the right one, but it should totally be doable.

JQuery If condition (specific for a content slider)

I am new at JQuery and I have a specific question about the IF-THEN-ELSE fork.
The big problem for me is the syntax of this (I suck at Javascript). It would help me if anyone can "translate" the pseudo code into a JQuery (or Javascript) valide code.
The pseudo code:
IF "#Contentshowroom" css "left" is NOT > 1960px
THEN
On Click "#Forwardbutton" DO
animate "#Contentshowroom" css "left" =+980px
ELSE You can not click on the "#Forwardbutton"

Place the if() statement in the click handler for #Forwardbutton to test the left position of #Contentshowroom.
If you're using jQuery:
$('#Forwardbutton').click(function() {
var $Content = $('#Contentshowroom');
if( $Content.offset().left <= 1960 ) {
$Content.animate({ left: '+= 980' });
}
});
So now when you click the Forwardbutton, it will check the left .offset() position of the Contentshowroom to see if it is less than or equal to 1960px. And if so, it will animate the left position an additional 980px.
jQuery's .offset() method gives you the top/left positions relative to the body. If you want it relative to its parent container, then use jQuery's .position() method.

click doc
animate doc
offset doc
$("#Forwardbutton").click( function( e ){
// lookup is safe, no noticable performance cost.
// though a reference makes it more losely coupled.
// I'll leave it at your discretion.
var target = $("#Contentshowroom")
// NOTE: the offset parent should have position relative or absolute.
, leftPos = target.offset().left;
if ( leftPos < 1960 ) {
target.animate({
left : leftPos + 980
}); // see docs to tweak animation
} // else do nothing.
} );
Could also use e.preventDefault(); , but don't if it's not needed, it will safe you headaches if you add more listeners to your buttons and find out they're not working.

// first store contentShowroom and it's left property to save getting > 1
var contentShowroom = $('#Contentshowroom');
var showroomLeft = contentShowroom.css('left');
var forwardButton = $('#Forwardbutton');
if (showroomLeft <= 1960){
forwardButton.click(function(){
contentShowroom.animate({left: showroomLeft + 980);
}
}
else {
forwardButton.unbind('click');
}

if this is to be run once at the beginning then
if ( $('#Contentshowroom').offset().left > 1960 )
{
$('#Forwardbutton').click( function(){
$('#Contentshowroom').animate({left:'+=980'});
} );
}
else
{
// if the #Contentshowroom is a link then
$('#Contentshowroom').removeAttr('href');
// if the #Contentshowroom is a button then
// $('#Contentshowroom').attr('disabled',true);
}