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True/False depending on screen size dynamically?

I'm following a guide that allows Google Map screen to disable scrolling depending on the screen size. The only part i'm struggling is to write a code that dynamically changes the True/False value when i resize the screen manually.
This is the website that I followed the instruction but I can't seem to write the correct syntax code to produce the dynamic true false value depending on the screen size https://coderwall.com/p/pgm8xa/disable-google-maps-scrolling-on-mobile-layout
Part of the code that i need to use:
$(window).resize()
And then:
setOptions()
So I'm struggling to combine them together.
I have tried something like this:
var dragging = $(window).width(function resize() {
if (dragging > 560) {
return true;
} else {
return false;
}
});

The article you linked to is lacking important information as it fails to mention that $ is (presumably) jQuery. But you don't need jQuery at all.
What you can use instead is the MediaQueryList. It is similar to media queries in CSS, but it is a JavaScript API.
The following is an untested example of how you might use it with a MediaQueryList event listener. It sets the initial value and listens to changes to your media query with a handler that uses setOptions from the Google Maps API.
var mql = window.matchMedia('(min-width: 560px)');
var isDraggable = mql.matches;
var map;
function initMap() {
map = new google.maps.Map(document.getElementById('map'), {
draggable: isDraggable
});
}
function mqChange(e) {
map.setOptions({draggable: !!e.matches});
}
mql.addListener(mqChange);

You could add an event listener to the resize event and set a value of your variable whenever the size of the window is changed:
var dragging = false;
window.addEventListener('resize', function(event) {
dragging = window.innerWidth > 560;
});
Since you mentioned that you want to disable scrolling when the windows size extends a certain value, it might be easier to just do this. If you try it you can see in the console that the value changes whenever you resize your window):
window.addEventListener('resize', function(event) {
console.log(window.innerWidth);
if (window.innerWidth > 560) {
// disable scrolling or do whatever you want to do
}
});
BTW, in your code you do this:
if (dragging > 560) {
return true;
} else {
return false;
}
You can simplify this to:
return dragging > 560
Which is exactly the same.

You can use this function to get the width and height on a resize of the screen.
$(window).resize(function() {
$windowWidth = $(window).width();
$windowHeight = $(window).height();
// run other functions or code
});
But, if you want to only show/hide a html element based on the screen size, you can also use plain html/css.
<div id="maps"></div>
Css:
#media only screen and (max-width: 560px) {
#maps {
display: none;
}
}

you can use the matchMedia function to run a callback whenever the media query status is changing
var mql = window.matchMedia('(min-width: 700px)');
function mediaHandler(e) {
if (e.matches) {
/* the viewport is more than 700 pixels wide */
} else {
/* the viewport is 700 pixels wide or less */
}
}
mql.addListener(mediaHandler);

particle-slider logo won't resize in Safari

I'm loading a front-end site from Wordpress using a HTML 5 Blank Child Theme. I have a logo effect using particle slider for when I have a screen size of >960px; for screen sizes <960px I have a flat logo image. It all works fine on both Firefox and Google Chrome but when I re-size between logos on Safari the page has to be refreshed manually (i.e. by pressing cmd+r) before the PS effect shows again. The code was sourced from an original question I posted here - Original Stack Q&A
Here's the javascript code I'm now using -
particle-slider.php
<?php /* Template Name: particle-slider */ ?>
<!-- particle-slider template -->
<div id="particle-slider">
<div class="slides">
<div class="slide" data-src="<?php echo home_url(); ?>/wp-content/uploads/2017/10/havoc_logohight.png"></div>
</div>
<canvas class="draw" style="width: 100%; height: 100%;"></canvas>
</div>
<script type="text/javascript">
var ps = new ParticleSlider({ 'width':'1400', 'height': '600' });
// patch nextFrame to track failure/success
var nextFrameCalled = false;
ps.oldNextFrame = ps.nextFrame;
ps.nextFrame = function () {
try {
ps.oldNextFrame.apply(this, arguments);
nextFrameCalled = true;
} catch (e) {
console.log(e);
nextFrameCalled = false;
}
};
var addEvent = function (object, type, callback) {
if (object.addEventListener) {
object.addEventListener(type, callback, false);
} else if (object.attachEvent) {
object.attachEvent("on" + type, callback);
} else {
object["on" + type] = callback;
}
};
var oldWidth = window.innerWidth;
addEvent(window, 'resize', function () {
var newWidth = window.innerWidth;
if (newWidth >= 960 && oldWidth < 960) {
console.log("Restarting particle slider " + newWidth);
ps.resize();
if (!nextFrameCalled)
ps.nextFrame(); // force restart animation
else {
// ensure that nextFrameCalled is not still true from previous cycle
nextFrameCalled = false;
setTimeout(function () {
if (!nextFrameCalled)
ps.nextFrame(); // force restart animation
}, 100);
}
}
oldWidth = newWidth;
});
</script>
<div id="logo"> <img src="<?php echo home_url(); ?>/wp-content/uploads/2017/10/havoc_logo.png"> </div>
<!-- particle-slider template -->
I need the same effect as is seen on this site here - where the logo switches from particle to static as the page is re-sized. The particle logo re-appears perfectly.
All other relevant code is linked to the original question as nothing has changed. I'm not seeing anything in the console to suggest why it's not working.

The resize event can fire multiple times, and within that event anything you put in a setTimeout will get called after the current code block has executed. It's hard to say for sure without picking apart ParticleSlider, but I think the mix of global variables (nextFrameCalled, oldWidth) and callbacks firing out of your expected order is the cause.
I think the intention is to debounce the forced restart - you want to call ParticleSlider.nextFrame() but if it's already been called you want to wait 100ms first.
Looking at the answer you've adapted for this question that appears to be a workaround for the canvas element not being visible on requestAnimationFrame - that might still not be available after 100ms or after the ParticleSlider.nextFrame() has been called multiple times in an attempt to get it to fire.
From your original question and selected answer I think you need to ParticleSlider.init() to reset the component, but the flashing you're seeing is due to the fact that it takes a while to run every time it's called. ParticleSlider.nextFrame() doesn't take as long (and uses requestAnimationFrame to avoid jank) but doesn't create the canvas on resize in Safari.
So, to fix:
Use ParticleSlider.init()
Debounce the resize event so you're not firing it lots of times
Fire it once a short delay after the user has stopped firing resize events.
Code will be something like:
var timeout = null;
window.addEventListener('resize', function() {
// Clear any existing debounced re-init
clearTimeout(timeout);
// Set up a re-init to fire in 1/2 a secound
timeout = setTimeout(function() {
ps.init();
}, 500);
});
You'll still see the flash and the delay as the component re-initialises, but only once.
I'd add that ParticleSlider has been deprecated by the authors and replaced with NextParticle - probably to fix these kinds of issues (in fact it has specific features to handle resizing). As it is a paid for component I'd suggest asking them for the help with this, as you should get your money's worth (or switch to an open source component where you can fix these bugs yourself).

So, I've finally figured this out by retracing my steps using the Q&A from before. Previously there seemed to be an issue with some of the sample links but one appears to work now - example.
I went into the page inspector and noticed a few differences between the code firing this example and the one in the actual answer that was causing the logo to flicker like a light bulb. This is the code I have now put into the wordpress site -
<script type="text/javascript">
//wait until the DOM is ready to be queried
(function() {//document.addEventListener('DOMContentLoaded', function() { //DOM-ready callback
var ps, timeout;
var img1 = new Image();
img1.src = '<?php echo home_url(); ?>/wp-content/uploads/2017/10/havoc_logohight.png';//havoc_logo_e6os2n.png';
var imgs = [ img1 ];
handlePS();
window.addEventListener('resize', function() {
//https://davidwalsh.name/javascript-debounce-function
if (timeout) { //check if the timer has been set
clearTimeout(timeout); //clear the timer
}
//set a timer
timeout = setTimeout(handlePS, 250);
});
function handlePS() {
if (document.body.clientWidth >= 960) {
//check if ps is assigned as an instance of the ParticleSlider
if (ps != undefined && typeof ps !== null) {
ps.init(); //refresh the particle slider since it exists
console.log('called init on ps');
} else {
if (window.location.search.indexOf('d=1') > -1) {
debugger;
}
//otherwise create a new instance of the particle slider
ps = new ParticleSlider({
width: 1400,
height: 600,
imgs: imgs
});
}
}
else {
//when the flat logo is displayed, get rid of the particle slider instance
// delete ps;
ps = null;
}
}
})();
</script>
It now works fine across all the main browsers - Chrome/Safari/Firefox. It still feels a bit clunky as it pushes the rest of the page down whilst it is re-sizing and it takes probably a few seconds more than I'd like - not sure if there's a timer option to speed the reanimation up? Otherwise, everything is working fine.

Angular custom directives not working with external javascript plugin

I am creating a custom angular directive that will use the Image Tilt Effect plugin.
<tilt></tilt>
the template looks like this.
<li class="grid__item">
<div class="grid__img grid__img--example-1" >
<img src="img/3.jpg" class="tilt-effect" alt="grid01" data-tilt-options='{ "opacity" : 0.3, "extraImgs" : 3, "movement": { "perspective" : 1200, "translateX" : -5, "translateY" : -5, "rotateX" : -5, "rotateY" : -5 } }' />
</div>
The problem I have is this script that I am loading at the bottom of the page doesnt seem to be on when the custom directive is injected into the page.
<script src="js/tiltfx.js"></script>
If I try and move the script into the html fragment for the custom directive I get an Error: $compile:tplrt

I've created a wrapper directive for this the Image Tilt Effect plugin (fiddle).
When you have a DOM plugin you need to use in angular, don't use auto initialization, such as the data-tilt-options of this plugin, because they are hard to predict, and may cause weird behavior, memory leaks, etc... This plugin has a manual init method - new TiltFx(element, options), so we can use that.
Another problem is that this plugin must wait for angular to finish rendering, before it should be initialized. The simple fix is just using setTimeout or $timeout (if we need to update the digest cycle), to put the init at the end of the JS queue. We can also use mutation observers to do that, but that's out of this answer's scope.
One troubling aspect of using a DOM plugin in angular, is memory leaks. Plugins should have some sort of a cleaning mechanism. This plugin doesn't. So, you'll have to check for memory leaks, and if there are stray event handlers remove them, when the wrapped element is removed.
Directive code:
appModule.directive('tilt', function tilt() {
var ddo = {
template: '<div class="grid__img"><img class="tilt-effect" ng-src="{{imgSrc}}" alt="The image" />',
restrict: 'E',
replace: true,
scope: {
imgSrc: '#', // the image src
tiltOptions: '=?' // the tilt options object - optional
},
link: function (scope, $el) {
var img = $el[0].querySelector('img.tilt-effect'); // find the img element
var tilt;
setTimeout(function () { // wait 'till directive is rendered
tilt = new TiltFx(img, scope.tiltOptions); // apply tilt on image with options (if any)
});
$el.on('$destroy', function() {
// use tilt variable to perform cleanup on wrapper and img if needed
tilt = null;
});
}
};
return ddo;
});
Usage:
<div ng-app="tilt">
<tilt img-src="http://cdn.cutestpaw.com/wp-content/uploads/2013/12/Most-Famous-Felines-034.jpg" tilt-options='{ "opacity" : 0.3, "extraImgs" : 3, "movement": { "perspective" : 1500, "translateX" : -5, "translateY" : -5, "rotateX" : -5, "rotateY" : -5 } }'></tilt>
<tilt img-src="http://www.cats.org.uk/uploads/images/pages/photo_latest14.jpg"></tilt>
</div>
Don't forget that this plugin requires the container to have fixed width and height, for example:
.grid__img {
width: 400px;
height: 400px;
}

Change
<script src="js/tiltfx.js"></script>
to
<script ng-src="js/tiltfx.js"></script>

Resizing divs on window resize using AngularJS

I'm trying to use a directive to resize a few divs on my page (5 to be exact). They're all columns which I'd like to resize so they always stretch to the bottom of the window.
I used this as a guide: Window resize directive
Coming up with this:
app.directive('resize', ['$window', function($window) {
return {
link: function(scope, elem, attrs) {
scope.onResize = function() {
var padding = 30,
offset = elem.prop('offsetTop'),
height = $window.innerHeight - offset - padding;
elem.css({height: height + 'px'});
}
scope.onResize();
angular.element($window).bind('resize', function() {
scope.onResize();
})
}
}
}]);
I've given my divs the directive element identifier of "resize".
On load, it works great - all divs are correctly sized. But, on changing window size, only the last rendered div is resized. I'm guessing it's because the resize window event is being overwritten each time with the scope of each div in turn, and so by the time the page is loaded, the window resize event only refers to the last rendered div.
How would I go about it so the resize event applies to all divs and not just the last one?

While looking into a completely unrelated issue, I realised I just needed to set the scope:
app.directive('resize', ['$window', function($window) {
return {
scope: {},
link: function(scope, elem, attrs) {
....
}
}
}]);

Catch browser's "zoom" event in JavaScript

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'.