Prevent zoom cross-browser
JavascriptHtmlCssCross BrowserJavascript Problem Overview
For a map-like tool, I would like to disable the browser zooming feature. (I know that this is generally a bad idea, but for some specific website, it is needed).
I did it successfully by listening the keyboard shortcut CTRL + / CTRL - and adding e.preventDefault(), etc.
But this doesn't prevent from changing the zoom from the browser's Zoom menu.
I tried:
-
with CSS:
zoom: reset;It works for Chrome (see this page for a working example) but it doesn't work at all on Firefox. -
in various questions/answers, I also found
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">but this seems to work for mobile only.
How to prevent zooming cross-browser ?
Javascript Solutions
Solution 1 - Javascript
I haven't really found an "authoritative" answer, meaning a clear statement from browser developers. However, all answers to similar questions I've found (like this one or that one) suggest the same thing - the browser's zoom feature exists for the benefit of the users and some browsers (like Firefox) simply don't allow you, as a website creator, to take this option away from them.
This documentation might shed some light into why allowing authors to disable zoom might be a good idea on mobile devices, but not on desktops.
In short, you might need to prevent mobile devices from initially auto-zooming your website, if you know their calculated auto-zoom will be inappropriate. On desktops, there is no auto-zoom, so when users come to your website, they see it exactly as it was meant to be seen. If they then decide they need to zoom the page, there's no good reason to let you prevent them from doing so.
As for the solutions you've listed:
zoomis a non-standard property not supported by Firefox, and<meta name="viewport">is concerned only with devices on which layout viewport and visual viewport are not the same thing, i.e. mobile devices.
Solution 2 - Javascript
You can disable zoom in browser when using Ctrl + + or Ctrl + - or Ctrl + mouse wheel up or Ctrl + mouse wheel down with this code.
$(document).keydown(function(event) {
if (event.ctrlKey==true && (event.which == '61' || event.which == '107' || event.which == '173' || event.which == '109' || event.which == '187' || event.which == '189' ) ) {
event.preventDefault();
}
// 107 Num Key +
// 109 Num Key -
// 173 Min Key hyphen/underscore key
// 61 Plus key +/= key
});
$(window).bind('mousewheel DOMMouseScroll', function (event) {
if (event.ctrlKey == true) {
event.preventDefault();
}
});
Check a demo here: JSFiddle.
Solution 3 - Javascript
I think what you can do is, listen to browser zoom event(ctrl + "+") and then check for window.devicePixelRatio.
Then accordingly, apply HTML5 scale transformation on the body element to scale down by the same ratio. So, basically you cannot prevent the functionality but you can apply negative effect with the same magnitude.
POC Code:
<body style="position: absolute;margin: 0px;">
<div style="width: 300px; height: 200px; border: 1px solid black;">
Something is written here
</div>
<script>
var keyIncrease = [17, 61];
var keyDecrease = [17, 173];
var keyDefault = [17, 48];
var listenMultiKeypress = function(keys, callback){
var keyOn = [];
for(var i=0; i<keys.length; i++){
keyOn[i] = false;
}
addEventListener('keydown', function(e){
var keyCode = e.which;
console.log(keyCode);
var idx = keys.indexOf(keyCode);
if(idx!=-1){
keyOn[idx] = true;
}
console.log(keyOn);
for(var i=0; i<keyOn.length; i++){
if(!keyOn[i]){
return;
}
}
setTimeout(callback, 100);
});
addEventListener('keyup', function(e){
var keyCode = e.which;
var idx = keys.indexOf(keyCode);
if(idx!=-1){
keyOn[idx] = false;
}
console.log(keyOn);
});
};
var previousScale = 1;
var previousDevicePixelRatio;
var neutralizeZoom = function(){
//alert('caught');
var scale = 1/window.devicePixelRatio;
document.body.style.transform = 'scale('+(1/previousScale)+')';
document.body.style.transform = 'scale('+scale+')';
var widthDiff = parseInt(getComputedStyle(window.document.body).width)*(scale-1);
var heightDiff = parseInt(getComputedStyle(window.document.body).height)*(scale-1);
document.body.style.left = widthDiff/2 + 'px';
document.body.style.top = heightDiff/2 + 'px';
previousScale = scale;
};
listenMultiKeypress(keyIncrease, neutralizeZoom);
listenMultiKeypress(keyDecrease, neutralizeZoom);
listenMultiKeypress(keyDefault, neutralizeZoom);
neutralizeZoom();
</script>
</body>
</html>
Solution 4 - Javascript
Insert the following into your HTML:
For Mobiles: Insert between the '< head>...< /head>' tag.
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, shrink-to-fit=no">
For Desktops across-Browsers: Insert just after start '< body>...' tag.
<script>
document.body.addEventListener("wheel", e=>{
if(e.ctrlKey)
e.preventDefault();//prevent zoom
});
</script>
Solution 5 - Javascript
So, as has been mentioned, that really isn't possible. However, there are some ways you can still be smart about it.
Three of the five major browsers all allow you to see the zoom level of the browser, furthermore, should the browser be zoomed a window.onresize event is fired.
IE: event.view.devicePixelRatio OR window.view.devicePixelRatio
Chrome: event.currentTarget.devicePixelRatio OR window.devicePixelRatio
Firefox: event.originalTarget.devicePixelRatio OR window.devicePixelRatio
Safari: /* Not possible */
Opera: /* Not possible */
I think the stuff after OR works based on something I noticed as I was messing around. The first ones I know work in at least the latest version of each one. Note that Safari and Opera both have the devicePixelRatio, however both never change. It's always just 1.
The above is your easy way if you don't care that much. If you do, then you could try out the detect-zoom script, which I came across while looking for solutions to Safari and Opera.
So what you can now do is get the zoom level, and then offset your zoom to where it doesn't do anything. So if I force my browser to 50% zoom, you just go to 200%. Thus, no change. Of course it will be a bit more complicated, you'll have to store the last browser zoom, the new browser zoom, and do some slightly more complicated math, but based on what you already have, that should be a breeze.
Another idea might be to just listen for a resize event, and calculate based off the new visible size, but that might cause issues if the window is just resized. I think the above is going to be your best option, with perhaps a fallback alert to warn the user not to zoom if necessary.
Solution 6 - Javascript
I updated code Vijay code:
$(document).ready(function(){
var keyCodes = [61, 107, 173, 109, 187, 189];
$(document).keydown(function(event) {
if (event.ctrlKey==true && (keyCodes.indexOf(event.which) != -1)) {
alert('disabling zooming');
event.preventDefault();
}
});
$(window).bind('mousewheel DOMMouseScroll', function (event) {
if (event.ctrlKey == true) {
alert('disabling zooming');
event.preventDefault();
}
});
});
This solution is cross-platform (OS / Win) for desktop browsers.
Solution 7 - Javascript
Have you tried ...
$("body").css({
"-moz-transform":"scale(1)",
"-webkit-transform":"scale(1)",
"-o-transform":"scale(1)",
"-ms-transform":"scale(1)"
});
I've used this type of code to set or re-set the scale.
Solution 8 - Javascript
$(document).ready(function () {
$(document).keydown(function (event) {
if (event.ctrlKey == true && (event.which == '107' || event.which == '109' || event.which == '187' || event.which == '189'))
{
event.preventDefault();
}
});
$(window).bind('mousewheel DOMMouseScroll', function (event) {
if (event.ctrlKey == true) {
event.preventDefault();
}
});
})
Solution 9 - Javascript
It is simple:
function load(){
document.body.addEventListener("wheel", zoomShortcut); //add the event
}
function zoomShortcut(e){
if(e.ctrlKey){ //[ctrl] pressed?
event.preventDefault(); //prevent zoom
if(e.deltaY<0){ //scrolling up?
//do something..
return false;
}
if(e.deltaY>0){ //scrolling down?
//do something..
return false;
}
}
}
p {
display: block;
background-color: #eeeeee;
height: 100px;
}
<!DOCTYPE html>
<html>
<head>
<title>Mousewheel control!</title>
</head>
<body onload="load()">
<p>If your Mouse is in this Box, you can't zoom.</p>
</body>
</html>
Solution 10 - Javascript
Prevent browser zooming by keyboard is as same as above many answers.
window.addEventListener('keydown', function (e) {
if ((e.ctrlKey || e.metaKey) && (e.which === 61 || e.which === 107 || e.which === 173 || e.which === 109 || e.which === 187 || e.which === 189)) {
e.preventDefault();
}
}, false);
But prevent zooming by mouse wheel is different in modern browser now. The new policy of Chrome need you use passive = false explicitly.
{passive: false}
If not， event.preventDefault（） can't stop the default action browser zooming by mouse wheel event, check it.
const handleWheel = function(e) {
if(e.ctrlKey || e.metaKey)
e.preventDefault();
};
window.addEventListener("wheel", handleWheel, {passive: false});
But we can’t prevent clicking to zoom from the browser menu.
Solution 11 - Javascript
This disables it for chrome and safari. I haven't tested it on other browsers https://jsfiddle.net/gjqpLfht/
$(document).ready(function() {
$(document).keydown(function(event) {
if (event.ctrlKey == true && (event.which == '61' || event.which == '107' || event.which == '173' || event.which == '109' || event.which == '187' || event.which == '189')) {
alert('disabling zooming');
event.preventDefault();
// 107 Num Key +
//109 Num Key -
//173 Min Key hyphen/underscor Hey
// 61 Plus key +/=
}
});
$(window).bind('mousewheel DOMMouseScroll', function(event) {
if (event.ctrlKey == true) {
alert('disabling zooming');
event.preventDefault();
}
});
});
document.addEventListener("gesturestart", function(e) {
e.preventDefault();
document.body.style.zoom = 0.99;
});
document.addEventListener("gesturechange", function(e) {
e.preventDefault();
document.body.style.zoom = 0.99;
});
document.addEventListener("gestureend", function(e) {
e.preventDefault();
document.body.style.zoom = 1;
});