Related
I want to provide my visitors the ability to see images in high quality, is there any way I can detect the window size?
Or better yet, the viewport size of the browser with JavaScript? See green area here:
Cross-browser #media (width) and #media (height) values
const vw = Math.max(document.documentElement.clientWidth || 0, window.innerWidth || 0)
const vh = Math.max(document.documentElement.clientHeight || 0, window.innerHeight || 0)
window.innerWidth and window.innerHeight
gets CSS viewport #media (width) and #media (height) which include scrollbars
initial-scale and zoom variations may cause mobile values to wrongly scale down to what PPK calls the visual viewport and be smaller than the #media values
zoom may cause values to be 1px off due to native rounding
undefined in IE8-
document.documentElement.clientWidth and .clientHeight
equals CSS viewport width minus scrollbar width
matches #media (width) and #media (height) when there is no scrollbar
same as jQuery(window).width() which jQuery calls the browser viewport
available cross-browser
inaccurate if doctype is missing
Resources
Live outputs for various dimensions
verge uses cross-browser viewport techniques
actual uses matchMedia to obtain precise dimensions in any unit
jQuery dimension functions
$(window).width() and $(window).height()
You can use the window.innerWidth and window.innerHeight properties.
If you aren't using jQuery, it gets ugly. Here's a snippet that should work on all new browsers. The behavior is different in Quirks mode and standards mode in IE. This takes care of it.
var elem = (document.compatMode === "CSS1Compat") ?
document.documentElement :
document.body;
var height = elem.clientHeight;
var width = elem.clientWidth;
I looked and found a cross browser way:
function myFunction(){
if(window.innerWidth !== undefined && window.innerHeight !== undefined) {
var w = window.innerWidth;
var h = window.innerHeight;
} else {
var w = document.documentElement.clientWidth;
var h = document.documentElement.clientHeight;
}
var txt = "Page size: width=" + w + ", height=" + h;
document.getElementById("demo").innerHTML = txt;
}
<!DOCTYPE html>
<html>
<body onresize="myFunction()" onload="myFunction()">
<p>
Try to resize the page.
</p>
<p id="demo">
</p>
</body>
</html>
I know this has an acceptable answer, but I ran into a situation where clientWidth didn't work, as iPhone (at least mine) returned 980, not 320, so I used window.screen.width. I was working on existing site, being made "responsive" and needed to force larger browsers to use a different meta-viewport.
Hope this helps someone, it may not be perfect, but it works in my testing on iOs and Android.
//sweet hack to set meta viewport for desktop sites squeezing down to mobile that are big and have a fixed width
//first see if they have window.screen.width avail
(function() {
if (window.screen.width)
{
var setViewport = {
//smaller devices
phone: 'width=device-width,initial-scale=1,maximum-scale=1,user-scalable=no',
//bigger ones, be sure to set width to the needed and likely hardcoded width of your site at large breakpoints
other: 'width=1045,user-scalable=yes',
//current browser width
widthDevice: window.screen.width,
//your css breakpoint for mobile, etc. non-mobile first
widthMin: 560,
//add the tag based on above vars and environment
setMeta: function () {
var params = (this.widthDevice <= this.widthMin) ? this.phone : this.other;
var head = document.getElementsByTagName("head")[0];
var viewport = document.createElement('meta');
viewport.setAttribute('name','viewport');
viewport.setAttribute('content',params);
head.appendChild(viewport);
}
}
//call it
setViewport.setMeta();
}
}).call(this);
I was able to find a definitive answer in JavaScript: The Definitive Guide, 6th Edition by O'Reilly, p. 391:
This solution works even in Quirks mode, while ryanve and ScottEvernden's current solution do not.
function getViewportSize(w) {
// Use the specified window or the current window if no argument
w = w || window;
// This works for all browsers except IE8 and before
if (w.innerWidth != null) return { w: w.innerWidth, h: w.innerHeight };
// For IE (or any browser) in Standards mode
var d = w.document;
if (document.compatMode == "CSS1Compat")
return { w: d.documentElement.clientWidth,
h: d.documentElement.clientHeight };
// For browsers in Quirks mode
return { w: d.body.clientWidth, h: d.body.clientHeight };
}
except for the fact that I wonder why the line if (document.compatMode == "CSS1Compat") is not if (d.compatMode == "CSS1Compat"), everything looks good.
If you are looking for non-jQuery solution that gives correct values in virtual pixels on mobile, and you think that plain window.innerHeight or document.documentElement.clientHeight can solve your problem, please study this link first: https://tripleodeon.com/assets/2011/12/table.html
The developer has done good testing that reveals the problem: you can get unexpected values for Android/iOS, landscape/portrait, normal/high density displays.
My current answer is not silver bullet yet (//todo), but rather a warning to those who are going to quickly copy-paste any given solution from this thread into production code.
I was looking for page width in virtual pixels on mobile, and I've found the only working code is (unexpectedly!) window.outerWidth. I will later examine this table for correct solution giving height excluding navigation bar, when I have time.
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' ] };
}
NB : to read the width, use console.log('viewport width'+viewport().width);
There is a difference between window.innerHeight and document.documentElement.clientHeight. The first includes the height of the horizontal scrollbar.
A solution that would conform to W3C standards would be to create a transparent div (for example dynamically with JavaScript), set its width and height to 100vw/100vh (Viewport units) and then get its offsetWidth and offsetHeight. After that, the element can be removed again. This will not work in older browsers because the viewport units are relatively new, but if you don't care about them but about (soon-to-be) standards instead, you could definitely go this way:
var objNode = document.createElement("div");
objNode.style.width = "100vw";
objNode.style.height = "100vh";
document.body.appendChild(objNode);
var intViewportWidth = objNode.offsetWidth;
var intViewportHeight = objNode.offsetHeight;
document.body.removeChild(objNode);
Of course, you could also set objNode.style.position = "fixed" and then use 100% as width/height - this should have the same effect and improve compatibility to some extent. Also, setting position to fixed might be a good idea in general, because otherwise the div will be invisible but consume some space, which will lead to scrollbars appearing etc.
For detect the Size dynamically
You can do it In Native away, without Jquery or extras
console.log('height default :'+window.visualViewport.height)
console.log('width default :'+window.visualViewport.width)
window.addEventListener('resize',(e)=>{
console.log( `width: ${e.target.visualViewport.width}px`);
console.log( `height: ${e.target.visualViewport.height}px`);
});
This is the way I do it, I tried it in IE 8 -> 10, FF 35, Chrome 40, it will work very smooth in all modern browsers (as window.innerWidth is defined) and in IE 8 (with no window.innerWidth) it works smooth as well, any issue (like flashing because of overflow: "hidden"), please report it. I'm not really interested on the viewport height as I made this function just to workaround some responsive tools, but it might be implemented. Hope it helps, I appreciate comments and suggestions.
function viewportWidth () {
if (window.innerWidth) return window.innerWidth;
var
doc = document,
html = doc && doc.documentElement,
body = doc && (doc.body || doc.getElementsByTagName("body")[0]),
getWidth = function (elm) {
if (!elm) return 0;
var setOverflow = function (style, value) {
var oldValue = style.overflow;
style.overflow = value;
return oldValue || "";
}, style = elm.style, oldValue = setOverflow(style, "hidden"), width = elm.clientWidth || 0;
setOverflow(style, oldValue);
return width;
};
return Math.max(
getWidth(html),
getWidth(body)
);
}
If you are using React, then with latest version of react hooks, you could use this.
// Usage
function App() {
const size = useWindowSize();
return (
<div>
{size.width}px / {size.height}px
</div>
);
}
https://usehooks.com/useWindowSize/
It should be
let vw = document.documentElement.clientWidth;
let vh = document.documentElement.clientHeight;
understand viewport: https://developer.mozilla.org/en-US/docs/Web/CSS/Viewport_concepts
shorthand for link above: viewport.moz.one
I've built a site for testing on devices: https://vp.moz.one
you can use
window.addEventListener('resize' , yourfunction);
it will runs yourfunction when the window resizes.
when you use window.innerWidth or document.documentElement.clientWidth it is read only.
you can use if statement in yourfunction and make it better.
You can simply use the JavaScript window.matchMedia() method to detect a mobile device based on the CSS media query. This is the best and most reliable way to detect mobile devices.
The following example will show you how this method actually works:
<script>
$(document).ready(function(){
if(window.matchMedia("(max-width: 767px)").matches){
// The viewport is less than 768 pixels wide
alert("This is a mobile device.");
} else{
// The viewport is at least 768 pixels wide
alert("This is a tablet or desktop.");
}
});
</script>
The problem
I'm using javascript to calculate widths of elements to achieve the layout I'm after. The problem is, I don't want to load the code on smaller screen sizes (when the screen width is less than 480px for example). I'd like this to work on load and on browser/viewport resize.
I'd consider small screen devices 'the default' and working up from there. So, none of the following script is called by default, then if the browser width is greater than 480px (for example), the following script would be called:
The code
$(document).ready(function() {
//Get the figures width
var figure_width = $(".project-index figure").css("width").replace("px", "");
//Get num figures
var num_figures = $(".project-index figure").length;
//Work out how manay figures per row
var num_row_figures = Math.ceil(num_figures / 2);
//Get the total width
var row_width = figure_width * num_row_figures;
//Set container width to half the total
$(".project-index").width(row_width);
x = null;
y = null;
$(".project-index div").mousedown(function(e) {
x = e.clientX;
y = e.clientY;
});
$(".project-index div").mouseup(function(e) {
if (x == e.clientX && y == e.clientY) {
//alert($(this).next().attr("href"));
window.location.assign($(this).next().attr("href"));
}
x = y = null;
});
});
// Drag-on content
jQuery(document).ready(function() {
jQuery('#main').dragOn();
});
The extra bit
The slight difference on larger screens is to do with the browser/viewport height. This is in regards to the line:
var num_row_figures = Math.ceil(num_figures / 2);
You can see once the calculation has a value, it divides it by 2. I only want this to happen when the browser/viewport height is above a certain amount - say 600px.
I'd be happy with this being the 1st state and then the value is divided by 2 if the height is greater than 600px if it's easier.
Can anyone help me/shed some light on how to manage my script this way. I know there's media queries for managing CSS but I can't seem to find any resources for how to manage javascript this way - hope someone can help.
Cheers,
Steve
You can use window.matchMedia, which is the javascript equivalent of media queries. The matchMedia call creates a mediaQueryList object. We can query the mediaQueryList object matches property to get the state, and attach an event handler using mediaQueryList.addListener to track changes.
I've added an example on fiddle of using matchMedia on load and on resize. Change the bottom left pane height and width (using the borders), and see the states of the two queries.
This is the code I've used:
<div>Min width 400: <span id="minWidth400"></span></div>
<div>Min height 600: <span id="minHeight600"></span></div>
var matchMinWidth400 = window.matchMedia("(min-width: 400px)"); // create a MediaQueryList
var matchMinHeight600 = window.matchMedia("(min-height: 600px)"); // create a MediaQueryList
var minWidth400Status = document.getElementById('minWidth400');
var minHeight600Status = document.getElementById('minHeight600');
function updateMinWidth400(state) {
minWidth400Status.innerText = state;
}
function updateMinHeight600(state) {
minHeight600Status.innerText = state;
}
updateMinWidth400(matchMinWidth400.matches); // check match on load
updateMinHeight600(matchMinHeight600.matches); // check match on load
matchMinWidth400.addListener(function(MediaQueryListEvent) { // check match on resize
updateMinWidth400(MediaQueryListEvent.matches);
});
matchMinHeight600.addListener(function(MediaQueryListEvent) { // check match on resize
updateMinHeight600(MediaQueryListEvent.matches);
});
#media screen and (max-width: 300px) {
body {
background-color: lightblue;
}
}
So i searched a bit and came up with this example from w3 schools .http://www.w3schools.com/cssref/tryit.asp?filename=trycss3_media_example1
i think this is something you are trying to achieve.
For pure js , you can get the screen width by screen.width
How do I auto-detect a screen resolution and change browser zoom with Javascript?
I was thinking of something more like this:
I've got the following code:
#warp with width: 3300% and a mask with width: 100%; and then, each .item has width: 3.030303% — with overflow hidden, otherwise it couldn't work as I want.
My point is: I've done this for at least 1280px wide screens.
What I want is if someone can write code that I could use toswitch the CSS file once viewed on a <1280px screen — them, I could do something like:
.item img { width: 80%; } and then, the result would be the same as "browser zoom out".
If you mean change the native browser zoom triggered by CTRL +/- then this isn't possible. You can adjust CSS properties/apply stylesheets but you cannot affect native browser controls. There are in fact CSS only options here depending on your target audience (and their browser choice) through the use of media queries, a couple of examples here and here. If these are not suitable then you can do various things with JavaScript to detect screen width/height and adjust accordingly.
Auto-detect a screen resolution
See this SO question
change browser zoom with javascript
This is not possible. See this SO question.
This will help to detect browser zoom tested on all browser
<script>
window.utility = function(utility){
utility.screen = {
rtime : new Date(1, 1, 2000, 12,00,00),
timeout : false,
delta : 200
};
utility.getBrowser = function(){
var $b = $.browser;
$.extend(utility.screen,$.browser);
utility.screen.isZoomed = false;
var screen = utility.screen;
screen.zoomf = screen.zoom = 1;
screen.width = window.screen.width;
screen.height = window.screen.height;
if($b.mozilla){ //FOR MOZILLA
screen.isZoomed = window.matchMedia('(max--moz-device-pixel-ratio:0.99), (min--moz-device-pixel-ratio:1.01)').matches;
} else {
if($b.chrome){ //FOR CHROME
screen.zoom = (window.outerWidth - 8) / window.innerWidth;
screen.isZoomed = (screen.zoom < .98 || screen.zoom > 1.02)
} else if($b.msie){//FOR IE7,IE8,IE9
var _screen = document.frames.screen;
screen.zoom = ((((_screen.deviceXDPI / _screen.systemXDPI) * 100 + 0.9).toFixed())/100);
screen.isZoomed = (screen.zoom < .98 || screen.zoom > 1.02);
if(screen.isZoomed) screen.zoomf = screen.zoom;
screen.width = window.screen.width*screen.zoomf;
screen.height = window.screen.height*screen.zoomf;
}
}
return utility.screen;
};
window.onresize = function(e){
utility.screen.rtime = new Date();
if (utility.screen.timeout === false) {
utility.screen.timeout = true;
setTimeout(window.resizeend, utility.screen.delta);
}
};
window.resizeend = function() {
if (new Date() - utility.screen.rtime < utility.screen.delta) {
setTimeout(window.resizeend, utility.screen.delta);
} else {
utility.screen.timeout = false;
utility.screen = utility.getBrowser();
if(window.onresizeend) window.onresizeend (utility.screen);
if(utility.onResize) utility.onResize(utility.screen);
}
};
window.onresizeend = function(screen){
if(screen.isZoomed)
$('body').text('zoom is not 100%');
else{
$('body').text('zoom is 100% & browser resolution is'+[screen.width+'X'+screen.height]);
}
};
$(document).ready(function(){
window.onresize();
});
return utility;
}({});
</script>
Demo
RE: Auto-detect a screen resolution and change browser zoom with Javascript?
The question is perfectly possible and is in effect at our website here:
www.noteswithwings.com
JS detects the screen width and zooms out or in a little to fit the content on to the screen.
Further, if the user resizes the window the zoom is triggered.
This actually helps fit content on to tablet sized screens and screens as small as the iphone without adding extra stylesheets or having to detect an OS/ Browser..
var oldZoom = $(window).width();
var windowWidth = $(window).width();
check_window_size(windowWidth,1,bsr,bsr_ver);
$(window).resize(function() {
var windowWidthnow = $(window).width();
check_window_size(windowWidthnow,2,bsr,bsr_ver);
});
function check_window_size(size,init_var,bsr,bsr_ver)
{
/* Develop for resizing page to avoid grey border!
Page layout 1265px wide.
On page resize shift layout to keep central, zoom BG-img to fill screen
Zoom content down for smaller screens by 5% to keep content flow!
*/
//change this var for screen width to work with, in this case our site is built at 1265
var wdth = 1265;
//Change this variable for minimum screen;
var smallest_width=1120;
var varZoom= $(window).width()/wdth;
var s_size = $(window).width();
var scale_smaller;
var center = (s_size-wdth)/2;
var its_ie=false;
if(size<=smallest_width)
{
$("#old_browser").css("width","50%").css({"height":"40px","left": center+"px"});
if(!check_for_object(false,"moved_pages"))
{
if(center<-110)//margin width!
{
if(!its_ie)
$("#scroller").css("zoom",0.95);
$("#footer").css("zoom",0.9).css("left",120+"px");
$(".colmask").css("left",-110+"px");
if(check_for_object(false,"move_menu_loggedin"))
$("#move_menu_loggedin").css("right","110px");
if(check_for_object(false,"login_div"))
$("#login_div").css("left","-80px");
return;
}
$("#move_menu_loggedin").css("left","-"+center+"px");
$("#scroll").css("zoom","normal");
$(".colmask").css("left",center+"px");
}
else
{
/*Only pages that you do not want to move the colmask for!*/
$("#scroller").css("zoom",0.90);//.css("left","-50px");;
$("#footer").css("zoom","normal");
}
}
else
{
if(size>wdth)
$("#background").css("zoom",varZoom);
$("#scroller").css("zoom","normal");
$("#footer").css({"zoom":"normal","left":0});
if(!check_for_object(false,"moved_pages"))
{
$(".colmask").css("left",center+"px");
$(".colmask").css("zoom","normal");
var movelog = -center;
if(check_for_object(false,"move_menu_loggedin"))
$("#move_menu_loggedin").css("right",movelog +"px");
if(check_for_object(false,"login_div"))
$("#login_div").css("left","80px");
}
else
{
$(".colmask").css("zoom","normal");
}
}
}
-- check_window_size(windowWidth,1,bsr,bsr_ver); bsr & bsr_ver are detected using a php class.
-- #old_browser is a div containing information if you have an old web browser.
-- #background is a fixed image 100x100% of the screen.
As you can see we also move a few items which were not in the containing div scope.
Colmask is the containing div for most of the pages content (For us that sits underneath the header which is why we move some items manually)
Hope the code snippet can help someone else achieve this.
Is it possible to detect, using JavaScript, when the user changes the zoom in a page?
I simply want to catch a "zoom" event and respond to it (similar to window.onresize event).
Thanks.
There's no way to actively detect if there's a zoom. I found a good entry here on how you can attempt to implement it.
I’ve found two ways of detecting the
zoom level. One way to detect zoom
level changes relies on the fact that
percentage values are not zoomed. A
percentage value is relative to the
viewport width, and thus unaffected by
page zoom. If you insert two elements,
one with a position in percentages,
and one with the same position in
pixels, they’ll move apart when the
page is zoomed. Find the ratio between
the positions of both elements and
you’ve got the zoom level. See test
case.
http://web.archive.org/web/20080723161031/http://novemberborn.net/javascript/page-zoom-ff3
You could also do it using the tools of the above post. The problem is you're more or less making educated guesses on whether or not the page has zoomed. This will work better in some browsers than other.
There's no way to tell if the page is zoomed if they load your page while zoomed.
Lets define px_ratio as below:
px ratio = ratio of physical pixel to css px.
if any one zoom The Page, the viewport pxes (px is different from pixel ) reduces and should be fit to The screen so the ratio (physical pixel / CSS_px ) must get bigger.
but in window Resizing, screen size reduces as well as pxes. so the ratio will maintain.
zooming: trigger windows.resize event --> and change px_ratio
but
resizing: trigger windows.resize event --> doesn’t change px_ratio
//for zoom detection
px_ratio = window.devicePixelRatio || window.screen.availWidth / document.documentElement.clientWidth;
$(window).resize(function(){isZooming();});
function isZooming(){
var newPx_ratio = window.devicePixelRatio || window.screen.availWidth / document.documentElement.clientWidth;
if(newPx_ratio != px_ratio){
px_ratio = newPx_ratio;
console.log("zooming");
return true;
}else{
console.log("just resizing");
return false;
}
}
The key point is difference between CSS PX and Physical Pixel.
https://gist.github.com/abilogos/66aba96bb0fb27ab3ed4a13245817d1e
Good news everyone some people! Newer browsers will trigger a window resize event when the zoom is changed.
I'm using this piece of JavaScript to react to Zoom "events".
It polls the window width.
(As somewhat suggested on this page (which Ian Elliott linked to): http://novemberborn.net/javascript/page-zoom-ff3 [archive])
Tested with Chrome, Firefox 3.6 and Opera, not IE.
Regards, Magnus
var zoomListeners = [];
(function(){
// Poll the pixel width of the window; invoke zoom listeners
// if the width has been changed.
var lastWidth = 0;
function pollZoomFireEvent() {
var widthNow = jQuery(window).width();
if (lastWidth == widthNow) return;
lastWidth = widthNow;
// Length changed, user must have zoomed, invoke listeners.
for (i = zoomListeners.length - 1; i >= 0; --i) {
zoomListeners[i]();
}
}
setInterval(pollZoomFireEvent, 100);
})();
This works for me:
var deviceXDPI = screen.deviceXDPI;
setInterval(function(){
if(screen.deviceXDPI != deviceXDPI){
deviceXDPI = screen.deviceXDPI;
... there was a resize ...
}
}, 500);
It's only needed on IE8. All the other browsers naturally generate a resize event.
There is a nifty plugin built from yonran that can do the detection. Here is his previously answered question on StackOverflow. It works for most of the browsers. Application is as simple as this:
window.onresize = function onresize() {
var r = DetectZoom.ratios();
zoomLevel.innerHTML =
"Zoom level: " + r.zoom +
(r.zoom !== r.devicePxPerCssPx
? "; device to CSS pixel ratio: " + r.devicePxPerCssPx
: "");
}
Demo
Although this is a 9 yr old question, the problem persists!
I have been detecting resize while excluding zoom in a project, so I edited my code to make it work to detect both resize and zoom exclusive from one another. It works most of the time, so if most is good enough for your project, then this should be helpful! It detects zooming 100% of the time in what I've tested so far. The only issue is that if the user gets crazy (ie. spastically resizing the window) or the window lags it may fire as a zoom instead of a window resize.
It works by detecting a change in window.outerWidth or window.outerHeight as window resizing while detecting a change in window.innerWidth or window.innerHeight independent from window resizing as a zoom.
//init object to store window properties
var windowSize = {
w: window.outerWidth,
h: window.outerHeight,
iw: window.innerWidth,
ih: window.innerHeight
};
window.addEventListener("resize", function() {
//if window resizes
if (window.outerWidth !== windowSize.w || window.outerHeight !== windowSize.h) {
windowSize.w = window.outerWidth; // update object with current window properties
windowSize.h = window.outerHeight;
windowSize.iw = window.innerWidth;
windowSize.ih = window.innerHeight;
console.log("you're resizing"); //output
}
//if the window doesn't resize but the content inside does by + or - 5%
else if (window.innerWidth + window.innerWidth * .05 < windowSize.iw ||
window.innerWidth - window.innerWidth * .05 > windowSize.iw) {
console.log("you're zooming")
windowSize.iw = window.innerWidth;
}
}, false);
Note: My solution is like KajMagnus's, but this has worked better for me.
⬤ The resize event works on modern browsers by attaching the event on window, and then reading values of thebody, or other element with for example (.getBoundingClientRect()).
In some earlier browsers it was possible to register resize event
handlers on any HTML element. It is still possible to set onresize
attributes or use addEventListener() to set a handler on any element.
However, resize events are only fired on the window object (i.e.
returned by document.defaultView). Only handlers registered on the
window object will receive resize events.
⚠️ Do resize your tab, or zoom, to trigger this snippet:
window.addEventListener("resize", getSizes, false)
function getSizes(){
let body = document.body
body.width = window.innerWidth
body.height = window.innerHeight
console.log(body.width +"px x "+ body.height + "px")
}
getSizes()
⬤ An other modern alternative: the ResizeObserver API
Depending your layout, you can watch for resizing on a particular element.
This works well on «responsive» layouts, because the container box get resized when zooming.
function watchBoxchange(e){
info.textContent = e[0].contentBoxSize[0].inlineSize+" x "+e[0].contentBoxSize[0].blockSize + "px"
}
new ResizeObserver(watchBoxchange).observe(fluid)
#fluid {
width: 200px;
height:100px;
overflow: auto;
resize: both;
border: 3px black solid;
display: flex;
flex-direction: column;
justify-content: center;
align-items: center;
font-size: 8vh
}
<div id="fluid">
<info id="info"></info>
</div>
💡 Be careful to not overload javascript tasks from user gestures events. Use requestAnimationFrame whenever you needs redraws.
I'd like to suggest an improvement to previous solution with tracking changes to window width. Instead of keeping your own array of event listeners you can use existing javascript event system and trigger your own event upon width change, and bind event handlers to it.
$(window).bind('myZoomEvent', function() { ... });
function pollZoomFireEvent()
{
if ( ... width changed ... ) {
$(window).trigger('myZoomEvent');
}
}
Throttle/debounce can help with reducing the rate of calls of your handler.
According to MDN, "matchMedia" is the proper way to do this https://developer.mozilla.org/en-US/docs/Web/API/Window/devicePixelRatio#Monitoring_screen_resolution_or_zoom_level_changes
it's a bit finicky because each instance can only watch one MQ at a time, so if you're interested in any zoom level change you need to make a bunch of matchers.. but since the browser is in charge to emitting the events it's probably still more performant than polling, and you could throttle or debounce the callback or pin it to an animation frame or something - here's an implementation that seems pretty snappy, feel free to swap in _throttle or whatever if you're already depending on that.
Run the code snippet and zoom in and out in your browser, note the updated value in the markup - I only tested this in Firefox! lemme know if you see any issues.
const el = document.querySelector('#dppx')
if ('matchMedia' in window) {
function observeZoom(cb, opts) {
opts = {
// first pass for defaults - range and granularity to capture all the zoom levels in desktop firefox
ceiling: 3,
floor: 0.3,
granularity: 0.05,
...opts
}
const precision = `${opts.granularity}`.split('.')[1].length
let val = opts.floor
const vals = []
while (val <= opts.ceiling) {
vals.push(val)
val = parseFloat((val + opts.granularity).toFixed(precision))
}
// construct a number of mediamatchers and assign CB to all of them
const mqls = vals.map(v => matchMedia(`(min-resolution: ${v}dppx)`))
// poor person's throttle
const throttle = 3
let last = performance.now()
mqls.forEach(mql => mql.addListener(function() {
console.debug(this, arguments)
const now = performance.now()
if (now - last > throttle) {
cb()
last = now
}
}))
}
observeZoom(function() {
el.innerText = window.devicePixelRatio
})
} else {
el.innerText = 'unable to observe zoom level changes, matchMedia is not supported'
}
<div id='dppx'>--</div>
You can also get the text resize events, and the zoom factor by injecting a div containing at least a non-breakable space (possibly, hidden), and regularly checking its height. If the height changes, the text size has changed, (and you know how much - this also fires, incidentally, if the window gets zoomed in full-page mode, and you still will get the correct zoom factor, with the same height / height ratio).
<script>
var zoomv = function() {
if(topRightqs.style.width=='200px){
alert ("zoom");
}
};
zoomv();
</script>
On iOS 10 it is possible to add an event listener to the touchmove event and to detect, if the page is zoomed with the current event.
var prevZoomFactorX;
var prevZoomFactorY;
element.addEventListener("touchmove", (ev) => {
let zoomFactorX = document.documentElement.clientWidth / window.innerWidth;
let zoomFactorY = document.documentElement.clientHeight / window.innerHeight;
let pageHasZoom = !(zoomFactorX === 1 && zoomFactorY === 1);
if(pageHasZoom) {
// page is zoomed
if(zoomFactorX !== prevZoomFactorX || zoomFactorY !== prevZoomFactorY) {
// page is zoomed with this event
}
}
prevZoomFactorX = zoomFactorX;
prevZoomFactorY = zoomFactorY;
});
Here is a clean solution:
// polyfill window.devicePixelRatio for IE
if(!window.devicePixelRatio){
Object.defineProperty(window,'devicePixelRatio',{
enumerable: true,
configurable: true,
get:function(){
return screen.deviceXDPI/screen.logicalXDPI;
}
});
}
var oldValue=window.devicePixelRatio;
window.addEventListener('resize',function(e){
var newValue=window.devicePixelRatio;
if(newValue!==oldValue){
// TODO polyfill CustomEvent for IE
var event=new CustomEvent('devicepixelratiochange');
event.oldValue=oldValue;
event.newValue=newValue;
oldValue=newValue;
window.dispatchEvent(event);
}
});
window.addEventListener('devicepixelratiochange',function(e){
console.log('devicePixelRatio changed from '+e.oldValue+' to '+e.newValue);
});
Here is a native way (major frameworks cannot zoom in Chrome, because they dont supports passive event behaviour)
//For Google Chrome
document.addEventListener("mousewheel", event => {
console.log(`wheel`);
if(event.ctrlKey == true)
{
event.preventDefault();
if(event.deltaY > 0) {
console.log('Down');
}else {
console.log('Up');
}
}
}, { passive: false });
// For Mozilla Firefox
document.addEventListener("DOMMouseScroll", event => {
console.log(`wheel`);
if(event.ctrlKey == true)
{
event.preventDefault();
if(event.detail > 0) {
console.log('Down');
}else {
console.log('Up');
}
}
}, { passive: false });
I'am replying to a 3 year old link but I guess here's a more acceptable answer,
Create .css file as,
#media screen and (max-width: 1000px)
{
// things you want to trigger when the screen is zoomed
}
EG:-
#media screen and (max-width: 1000px)
{
.classname
{
font-size:10px;
}
}
The above code makes the size of the font '10px' when the screen is zoomed to approximately 125%. You can check for different zoom level by changing the value of '1000px'.
How do I detect the width of a user's window with Javascript and account for their scrollbar? (I need the width of the screen INSIDE of the scrollbar). Here's what I have...it seems to work in multiple browsers...except that it doesn't account for the scrollbars..
function browserWidth() {
var myWidth = 0;
if( typeof( window.innerWidth ) == 'number' ) {
//Non-IE
myWidth = window.innerWidth;
} else if( document.documentElement && document.documentElement.clientWidth ) {
//IE 6+ in 'standards compliant mode'
myWidth = document.documentElement.clientWidth;
} else if( document.body && document.body.clientWidth ) {
//IE 4 compatible
myWidth = document.body.clientWidth;
}
return myWidth;
}
any ideas? i need it to work in all browsers;)
A (markedly nasty) workaround if you're only interested in the width is to create a 1px x 100% div and use its offsetWidth. Works on IE>=7, FF, Chrome, Safari and Opera (I've not tried IE6, as we're working to a you're-lucky-it-works-at-all-so-don't-complain-about-rendering-oddities policy thereabouts these days). I hang the div off document.body with attributes { position: 'absolute', top: '-1px', left: 0, width: '100%', height: '1px' }, creating it the first time it's needed.
Works if you can stomach it.
You will find the big summary of what properties are supported on what browsers on this page on quirksmode.org.
Your best bet is probably to grab an element in the page (using document.body where supported, or document.getElementById or whatever), walk its offsetParent chain to find the topmost element, then examine that element's clientWidth and clientHeight.
Just add that before the window.innerWidth() check:
if (typeof(document.body.clientWidth) == 'number') {
// newest gen browsers
width = document.body.clientWidth;
height = document.body.clientHeight;
}
This is what I did - only half a year into learning JavaScript, so this may be a bad fix. First, I created a transparent square image (10px x 10px), but you could also create a non-transparent image and add this to your JavaScript as
document.getElementById('getDimensions').style.visibility = "hidden";
HTML:
<img id="getDimensions" src="images/aSmallBox.png" alt="A small transparent image
meant to determine the dimensions of the viewport" width="10px" height="10px"/>
JavaScript:
//Inside function called by window.onload event handler (could go in CSS file, but
//better to keep it with other related code in JS file)
document.getElementById('getDimensions').style.position = "fixed";
document.getElementById('getDimensions').style.bottom = "0px";
document.getElementById('getDimensions').style.right = "0px";
//Everything below inside function called by window.onresize event handler
var baseWidthCalculation = document.getElementById('getDimensions').offsetLeft;
var baseHeightCalculation = document.getElementById('getDimensions').offsetTop;
//Account for the dimensions of the square img element (10x10)
var viewportWidth = baseWidthCalculation + 10;
var viewportHeight = baseHeightCalculation + 10;
This is a more efficient version of an idea posted here by Tim Salai ( even though you are just beginning, it was brilliant to place an element in the bottom right corner like that ).
var getDimensions = document.createElement("div");
getDimensions.setAttribute("style",
"visibility:hidden;position:fixed;bottom:0px;right:0px;");
document.getElementsByTagName("body")[0].appendChild(getDimensions);
var viewportWidth = getDimensions.offsetLeft;
var viewportHeight = getDimensions.offsetTop;
And here is a modular version
var PageDimensions = function(){
var Width;
var Height;
function pagedimensionsCtor (){
var getDimensions = document.createElement("div");
getDimensions.setAttribute("style" ,
"visibility:hidden;position:fixed;bottom:0px;right:0px;");
document.getElementsByTagName("body")[0].appendChild(getDimensions);
Width = getDimensions.offsetLeft;
Height = getDimensions.offsetTop;
getDimensions.parentNode.removeChild(getDimensions);
}
pagedimensionsCtor();
function Reset(){
pagedimensionsCtor();
}
function GetPageHeight(){
return Height;
}
function GetPageWidth(){
return Width;
}
return{
Reset: Reset,
GetPageHeight: GetPageHeight,
GetPageWidth: GetPageWidth
};
}
Use the modular version:
var page = new PageDimensions();
console.log("viewportWidth: " + page.GetPageWidth() + " viewportHeight: " + page.GetPageHeight());
Bonus feature:
page.Reset();//just in case you think your dimensions have changed
I would compare the "innerWidth" to the width of the body. If the body width > innerwidth, then scrollbars are present.
if (browserWidth() < document.body.offsetWidth) {
doSomething();
}
Another solution you can try is changing some CSS so scrolling happens within your page, instead of the browser window doing it. In the style for body, add overflow:auto. Now the body element includes the scrollbar, so when you get the window width you're measuring the width outside the scrolling container instead of inside it.
This does feel like a potential source of quirkiness, and possibly an accessibility issue, so if you're going for widespread use you might want to test it quite carefully.