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How to detect a browser screen width increase past a certain point using jQuery?

basically, what I want to do is trigger an event if the user increases the size of the browser from X to Y. Provided X = Anything less than 750 pixels, and Y is anything more than 750 pixels.
Right now, I am doing something like this:
$(window).resize(function(){
if ($(window).width() >= 750) {
console.log('750 or more');
}
});
This works, however, its clearly not efficient. For example, if I resize my window from 780px to max width (1024px), even then the event gets triggered. Or even if I decrease the size from 800px to 780px, I still obviously get the console output.
How do I get this to work right?

You will need to setTimeout to allow check to take place .
Example :
var resizeTimer;
$(window).resize(function() {
clearTimeout(resizeTimer);
resizeTimer = setTimeout(function() {
var body_size = $(window).width();
// ...
// do your screen check here
// ...
}, 1);
})
Hope this helps

There's no true solution for this issue since removing the on resize event after max width has been reached results in the on resize function no longer being called even when the width is below 1024px.
Maybe in the future it's possible to have an on resize event under certain conditions only.
You can also use the on resize end event to only trigger the function after resizing the window, keep in mind this might result in visual changes happening after a user has resized a window instead of during the resizing of a window.
There are multiple methods to make the on resize event perform better: http://bencentra.com/code/2015/02/27/optimizing-window-resize.html

Here is a throttled version using script that might be a good start
Fiddle demo
(function(timeout,bigger) { // local static var - timeout,bigger
window.addEventListener("resize", function(e) {
if ( !timeout ) {
timeout = setTimeout(function() {
timeout = null;
actualResizeHandler(e);
// Set the actual fire rate
}, 66);
}
}, false);
function actualResizeHandler(e) {
// handle the resize event
if (window.innerWidth >= 750 && !bigger) {
//passed above (or equal) 750
document.querySelector('span').style.color = 'blue';
document.body.innerHTML += '<br>above 750';
} else if (window.innerWidth < 750 && bigger) {
//passed below 750
document.querySelector('span').style.color = 'red';
document.body.innerHTML += '<br>below 750';
}
bigger = (window.innerWidth >= 750);
}
// run once at load
bigger = (window.innerWidth < 750);
actualResizeHandler();
}(null,false));
<span>This text is blue on big and red on small</span>
and here is one use CSS media query
span {
color: red;
}
#media screen and (min-width: 750px) {
span {
color: blue
}
}
<span>This text is blue on big and red on small</span>

Using jQuery in certain screen sizes

I need a mobile navigation to stick after the user has scrolled a certain amount. When a user has scrolled 205px on desktop resolution the navigation will stick no problem.
How do I change this to 64px after the screen size has gone below 767px? and how do I cancel the desktop jQuery from taking effect on a mobile?
Current desktop javascript:
$(window).scroll(function(){
if ($(this).scrollTop() > 205) {
$('.sidemenu').addClass('fixed');
} else {
$('.sidemenu').removeClass('fixed');
}
});
Current mobile javascript:
function checkPosition() {
if (window.matchMedia('(max-width: 767px)').matches) {
$(window).scroll(function(){
if ($(this).scrollTop() > 64) {
$('.sidemenu').addClass('fixed');
} else {
$('.sidemenu').removeClass('fixed');
}
})
}
};
Suggestions would be much appreciated.
Thank you.

You can add a class mobile to your body for example when the matchmedia matches.
$(document.body).toggleClass('mobile', window.matchMedia('(max-width: 767px)').matches);
Once you have that, the checkPosition simply has to get the proper scrollTop value.
function checkPosition() {
var scrollY = $(document.body).hasClass('mobile') ? 64 : 205;
$('.sidemenu').toggleClass('fixed', $(window).scrollTop() > scrollY);
};
Or simply add the matchMedia test instead of the hasClass test.
Additionally, I expect the height of the "fixed container" to be dynamic.
Maybe something like:
var scrollY = $('header').height(); // just an idea ofcourse to get 64 or 205.

You can check screens size in resize wvent like this
var width;
$(window).resize(function () {
width = $("html").width();
});
than in scroll event (or in other place) you can check:
if (width <= 767) {
// do some for small screen
}
else if (width > 767 && width < 1200) {
// do some for medium screen
}
//if..

scroll speed with mousewheel jquery plugin

I want to imitate the Google+ header with the search bar. When you scroll down it goes to top:-60px and the second horizontal menu will be top:0 from top:60px and become the main top horizontal menu, while the one with top:-60px remains hidden until we scroll to top.
I managed to do this, but it only works when I scroll slowly (with trackpad, OSX, Chrome33). I researched and found out the scroll speed depends on the hardware (touchpad, mouse), the OS and even on the browser. I found mousewheel plugin, that aims to make the scrolling speed equal but I can't make it work.
Here is the js code: ( The delta divisions I got from here: https://stackoverflow.com/a/16696129 )
<script type="text/javascript">
gn_top_menu_featured = $('.gn-top-menu-featured'),
gn_top_menu = $('.gn-top-menu'),
hide_gn_top_menu_featured = 0,
gn_top_menu_position = 44;
$('body').on('mousewheel', function(event) {
if( event.deltaX >= 40 )
event.deltaX /= 40;
if( event.deltaY >= 40 )
event.deltaY /= 40;
var sy = $('body').scrollTop();
if ( sy >= hide_gn_top_menu_featured && sy <= gn_top_menu_position ) {
gn_top_menu_featured.css('top', -sy);
gn_top_menu.css('top', gn_top_menu_position-sy);
}
else {
// whatever
}
});
</script>
I really want to get this working properly, thank in advance. :)

Turns out i misunderstood your problem at first. Here's another attempt at solving this. I still might not be understanding you correctly, because I still don't need to control the mousewheel speed to make this work. Here's the updated fiddle.
I use the $(window).scroll event to check the $(window).scrollTop() value and change the css class of the div.
$(window).scroll(function(){
$("#nav").css("top", ($(window).scrollTop() < 60 ? (60 - $(window).scrollTop()) : 0) + 'px');
if ($(window).scrollTop() > 60) {
$("#nav").addClass('sub-60').text('WOOT!');
}
else {
$("#nav").removeClass('sub-60').text('MAIN NAV');
}
});

How do I get the sidebar to move up

I have this page and I want the sidebar to slide down with the user and it works well but if you are on a small screen like 1024 * 768 you will not see the bottom. Here is some of the code I used to make the sidebar work. Any suggestions on how I can change this behavior.
$(window).scroll(function(){
sidebar_position();
});
$(window).resize(function(){
sidebar_position();
});
function sidebar_position(){
var w_width = ($(window).width() -1000) /2;
$('#sidebar').css('left', w_width);
var sidebar_height = $('#sidebar').outerHeight();
var content_height = $('#widecolumn').outerHeight();
var w_height = $(window).height();
if ( sidebar_height > w_height) {
$('#sidebar').css('position', 'absolute');
} else {
$('#sidebar').css('position', 'fixed');
};
if (sidebar_height > content_height) {
content_height = sidebar_height;
$('#widecolumn').css('min-height', content_height);
};
if($.browser.msie && $.browser.version == 6 ){
$(window).scroll(function(){
$('#sidebar').css({
top: $(window).scrollTop()
});
})
}
}
I am sort of lost of what to do next....and how to fix this

Hm small screens are a problem either way since the sidebar is almost 600 px high so on netbooks it probably won't fit in the browser window at all.
But you could leave the sidebar on position absolute until the sidebar reaches the top when scrolling and then switch to position fixed so it stays at the top of the screen.
That way it will use the available screen height

Keeping a page element in view while scrolling page

I'm looking for a solution to keep an element in view, while scrolling the rest of the page.
I don't want to re-invent the wheel so i'm reaching out to see if the community knows of a canned solution already.
I want to apply this to a huge table that I have, and I would like users to be able to continue seeing the table headers as they scroll down.
Just to clarify, what I'm looking for is different from a scrollable table with overflow CSS settings. The reason I can't use a scrollable table is because that method becomes very slow with thousands of rows. Also that method does not work well on the iPhone browser.
Ideally I would like it so that when the user scrolls the page down the table's header would 'stick' at the top edge of the browser's view. Inversely if the user scrolls back up it would continue to stick there until it arrives back at the original position the header started from.

Are you looking for the #element { position: fixed; ... }? You can switch between fixed, relative and absolute using JS.
http://www.w3schools.com/cssref/pr_class_position.asp
Edit
Take a look at how they do it on [I hope they don't mind] http://www.zocdoc.com/search.aspx?dr_specialty=98&address=Enter+a+City+and+State%2C+or+Zip&insurance_carrier=-1&insurance_plan=-1&button.x=166&button.y=21
They use jQuery, it doesn't seem complicated and they also has an IE6 workaround
$(function() {
var msie6 = $.browser.msie && $.browser.version < 7;
if (!msie6) {
var top = $('#scroll_header').offset().top
- parseFloat($('#scroll_header').css('margin-top').replace(
/auto/, 0));
$(window).scroll(function(event) {
var y = $(this).scrollTop();
if (y >= top) {
$('#scroll_header').addClass('fixed');
} else {
$('#scroll_header').removeClass('fixed');
}
});
var y = $(this).scrollTop();
if (y >= top) {
$('#scroll_header').addClass('fixed');
} else {
$('#scroll_header').removeClass('fixed');
}
} else {
setInterval("checkScroll()", 100);
}
});
function checkScroll() {
ie6top = $('#scroll_header_wrapper').offset().top;
if ($(document).scrollTop() > ie6top) {
$('#scroll_header').css("top", $(document).scrollTop() - ie6top + "px");
$('#scroll_header').css("visibility", "visible");
} else {
$('#scroll_header').css("visibility", "hidden");
}
}