Develop Reference

A javascript function to be executable on a specific screen size

Is it possible?
I have the following javascript function
<a onclick="execute()">Click here</a>
function execute(){
//code goes here
}
I would like that the onclick event to be only active when the screen size is below 768, so it's only relevant on mobile devices and so on.
Is it possible? and how do you achieve this?

It's totally possible. You'd probably want to do it in the execute function, otherwise when someone clicks on a larger size, there would be a ReferenceError (execute is not defined).
function execute () {
var width = window.innerWidth
if (width >= 768) return
// rest of code here
}

function execute(){
if(screen.width <= 768) {
//code goes here
}
}
Reference: https://www.w3schools.com/jsref/prop_screen_width.asp

Could also use a media query with CSS
#media only screen and (max-width: 768px) {
a {
display: none;
}
}
Media Queries

Different measurement between #media querys and jquery

I notticed when resizing the window, that the effects applied from the responsive #media querys and the effects applied from the jQuery are not at the same point of width.
Is is dued to the browser? Is there a solution for that, or a way to calculate the difference between CSS and JS?
My CSS:
#media only screen
and (min-width : 768px)
and (max-width : 1024px) { }
My jQuery:
$(document).ready(function(){
if($(this).width() < 1024 && $(this).width() > 768) {
} else {
}
$(window).on('resize', function(){
if($(this).width() < 1024 && $(this).width() > 768) {
} else {
}
});
});
To avoid this difference at the moment, my solution is something like that: I have a #selector declared with the display:none when it's between 768px and 1024px. Then, in the jQuery code, instead of using the size < 1024 and > 768 I'm using this:
if($("#selector").is(":hidden")) { }
But, is there a better way to combine width from the #media querys and the jQuery without differences? Thanks.
UPDATE: I already found a solution explained here: https://stackoverflow.com/a/11310353/3018860. That occurs because «the CSS is using the device width, but the JS is using the document width».

detect browser size and apply css for every resolution

I have this function that I use to apply some css to a menu when browser is resized or when the menu is rendering on different resolutions.
My problem is this, why the browser is not interpreting correctly my function? because when I resize my browser in full mode from half mode the browser interprets only '800-1024' resolution but if I do ctrl+f5 in browser (clear all) interprets correctly my resolution so what is wrong in my function?
function renderMenuCorection(){
if ($('#containerHeader').exists()) {
var resizeObject = {
'0-640': '9px,2px,-3px,12px',
'640-800': '10px,2px,-5px,12px',
'800-1024': '10px,8px,-8px,15px',
'1024-1300': '12px,12px,-13px,11px',
'1300-2000': ',20px,-21px'
}
var win = $(window);
var win_width = win.width();
if (win_width > 0 && win_width <= 640) {
var value = getValueByKey(resizeObject, '0-640');
modifayMenu(value);
}
else
if (win_width > 640 && win_width <= 800) {
var value = getValueByKey(resizeObject, '640-800');
modifayMenu(value);
}
else
if (win_width > 800 && win_width <= 1024) {
var value = getValueByKey(resizeObject, '800-1024');
modifayMenu(value);
alert("I'm on: 800-1024 ," + win_width);
}
else
if (win_width > 1024 && win_width <= 1300) {
var value = getValueByKey(resizeObject, '1024-1300');
modifayMenu(value);
alert("I'm on: 1024-1300 ," + win_width);
}
else
if (win_width > 1300 ) {
var value = getValueByKey(resizeObject, '1300-2000');
modifayMenu(value);
}
}
}
function modifayMenu(value){
var vals = value.split(',')
$('#containerHeader').find('.roundMenuLi').each(function(index, item){
$(item).find('a').css('font-size', vals[0]);
$(item).css('padding-right', vals[1]);
$(item).css('padding-left', vals[1]);
$(item).find('#secondUl').css('margin-left', vals[2]);
$(item).css('padding-bottom', vals[3]);
});
}
function getValueByKey(obj, myKey){
$.each(obj, function(key, value){
if (key == myKey) {
returnValue = value;
}
});
return returnValue;
}
Thank you !

Use CSS3 and its media queries. Example:
#media (max-width: 500px) {
/* some CSS for small resolution */
}
#media (min-width: 1000px) {
/* some CSS for large resolution */
}

you main you want to create a responsive design this link can help you.
building responsive design you must consider
Flexible Grid
Flexible Images
Media Quires
/* below code play important part of your responsive design without that you cannot achieve what you want */
<meta name="viewport" content="width=device-width" /> /* put this before the end tag of head */
#media (max-width: 320px) {
}
#media (min-width: 720px) {
}

It's hard to tell from your code, but most likely you are only calling the function once on pageload. In order to make this do what you want, you will have to attach an event listener and call the code each time the window is resized.
As commented above, consider researching Responsive Web Design to utilize native browser functionality so you don't have to roll your own script to do this. A good place to start is an A List Apart article under the same name.

Media-queries are the best solution as Pavel remarks, besides they're much faster than all the access to the DOM you're making using your code.
The compatibility problem with IE8 can be solved using a JavaScript pluging called Respond.js. Haven't tried it but it seems a good solution to your problem.

fix div width #media fix for IE

I have a div set to 100% width, and when the page is being looked at 1024 resolution the width should change from 100% to 1000px, I got it working properly with #media queries and works fine on FF, safari chrome. But ie8 and below ignores it, is there any other to try to get the div to change the width from 100% to 1000px at 1024 resolution on IE?
I tried this with jquery but doesn't work.
$(document).ready(function(){
if ($(window).width() < 1024) {
$('#content')css('width','1000px')
} else {
$('#content')css('width','100%')
};
}

media queries are CSS3. Means not supported by IE8 and lower. But take a look here, that brings support for media queries to IE.

$(document).load($(window).bind("resize", changeWidth));
function changeWidth( e ) {
if($(window).width()<1024)
{
$('#content').css('width','1000px');
} else {
$('#content').css('width','100%');
}
}
jsFiddle

Why not just set this in CSS:
width: 100%;
max-width: 1000px;
It's infinitely more efficient than any JS/jQuery solution, I can assure you.

you can use this code :
$(window).resize(function () {
var width = screen.width;
var height = screen.height;
if (width <= 1024) {
//somecode
} else {
//somecode
}
});
however,as Sven Bieder mentioned CSS Media Queries are better than for Responsive Design.

CSS media queries and jQuery window .width() do not match

For a responsive template, I have a media query in my CSS:
#media screen and (max-width: 960px) {
body{
/* something */
background: red;
}
}
And, I made a jQuery function on resize to log the width:
$(window).resize( function() {
console.log( $(window).width() );
console.log( $(document).width() ); /* same result */
/* something for my js navigation */
}
And there a difference with CSS detection and JS result, I have this meta:
<meta content="user-scalable=no, initial-scale=1.0, maximum-scale=1.0, width=device-width" name="viewport"/>
I suppose it's due to the scrollbar (15 px). How can I do this better?

You're correct about the scroll bar, it's because the CSS is using the device width, but the JS is using the document width.
What you need to do is measure the viewport width in your JS code instead of using the jQuery width function.
This code is from http://andylangton.co.uk/articles/javascript/get-viewport-size-javascript/
function viewport() {
var e = window, a = 'inner';
if (!('innerWidth' in window )) {
a = 'client';
e = document.documentElement || document.body;
}
return { width : e[ a+'Width' ] , height : e[ a+'Height' ] };
}

I found following code on http://www.w3schools.com/js/js_window.asp:
var w=window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth;
Practically its working the same way as the answer in #Michael Bird's answer, but it's more easy to read.
Edit: I was looking for a method to give exactly the same width as it is used for css media queries. But the suggested one does not work perfect on Safari with scrollbars, sorry. I ended up using modernizr.js in one central function and in the rest of the code I just check if display type is mobile, tablet or desktop. As I am not interested in the width, this works fine for me:
getDisplayType = function () {
if (Modernizr.mq('(min-width: 768px)')){
return 'desktop';
}
else if (Modernizr.mq('(min-width: 480px)')){
return 'tablet'
}
return 'mobile';
};

window.innerWidth is what you need.
if (window.innerWidth < 768) works for 768 break point in CSS

Workaround that always works and is synced with CSS media queries.
Add a div to body
<body>
...
<div class='check-media'></div>
...
</body>
Add style and change them by entering into specific media query
.check-media{
display:none;
width:0;
}
#media screen and (max-width: 768px) {
.check-media{
width:768px;
}
...
}
Then in JS check style that you are changing by entering into media query
if($('.check-media').width() == 768){
console.log('You are in (max-width: 768px)');
}else{
console.log('You are out of (max-width: 768px)');
}
So generally you can check any style that is being changed by entering into specific media query.

My experience was that the media query width tracks document.body.clientWidth. Because of a vertical scroll bar coming and going, checking document, window, or viewport().width could cause my Javascript to run late--after the media query rule change, depending on the height of the window.
Checking document.body.clientWidth allowed my script code to execute consistently at the same time the media query rule took effect.
#media (min-width:873px) {
//some rules
}
...
if ( document.body.clientWidth >= 873) {
// some code
}
The Andy Langton code put me onto this--thanks!

Hi i use this little trick to get JS and CSS work together easily on responsive pages :
Test the visibility of an element displayed or not on CSS #media size condition.
Using bootstrap CSS i test visibility of a hidden-xs class element
var msg = "a message for U";
/* At window load check initial size */
if ( $('#test-xsmall').is(':hidden') ) {
/* This is a CSS Xsmall situation ! */
msg = "#media CSS < 768px. JS width = " + $(window).width() + " red ! ";
$('.redthing-on-xsmall').addClass('redthing').html(msg);
} else {
/* > 768px according to CSS */
msg = "#media CSS > 767px. JS width = " + $(window).width() + " not red ! ";
$('.redthing-on-xsmall').removeClass('redthing').html(msg);
}
/* And again when window resize */
$(window).on('resize', function() {
if ($('#test-xsmall').is(':hidden')) {
msg = "#media CSS < 768px. JS width = " + $(window).width() + " red ! ";
$('.redthing-on-xsmall').addClass('redthing').html(msg);
} else {
msg = "#media CSS > 767px. JS width = " + $(window).width() + " not red ! ";
$('.redthing-on-xsmall').removeClass('redthing').html(msg);
}
});
#media (min-width: 768px) {
.hidden-xs {
display: block !important;
}
}
#media (max-width: 767px) {
.hidden-xs {
display: none !important;
}
}
.redthing-on-xsmall {
/* need a scrollbar to show window width diff between JS and css */
min-height: 1500px;
}
.redthing {
color: red;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<!-- the CSS managed Element that is tested by JS -->
<!-- class hidden-xs hides on xsmall screens (bootstrap) -->
<span id="test-xsmall" class="hidden-xs">THIS ELEMENT IS MANAGED BY CSS HIDDEN on #media lower than 767px</span>
<!-- the responsive element managed by Jquery -->
<div class="redthing-on-xsmall">THIS ELEMENT IS MANAGED BY JQUERY RED on #media max width 767px </div>

Css media query is equal to window.innerWidth. Css Media Queries calculate the scrollbar as well.

The simple and reliable way of doing this is to use Media Queries.
To demonstrate, I want to check if the screen width is greater than or equal to 992px (Bootstrap's large device):
function isLargeDevice() {
if (window.matchMedia("(min-width: 992px)").matches) {
return true;
}
return false;
}
If you are using Modernizer then it's a bit easier, here I want to check if the screen is smaller than Bootstrap's large screen (992px)
function isSmallerThanLargeScreen() {
if (Modernizr.mq('(max-width: 991px)')) {
return true;
}
return false;
}