How to disable page zoom using JavaScript

With the popularity of mobile devices, the issue of web page adaptation is becoming more and more important. One such issue is page scaling, which can cause inconvenience and confusion to users. Although most browsers provide the zoom function, in some scenarios it is necessary to prohibit users from zooming on the page. So, how to disable page zooming using JavaScript?

The first method is to use meta tags to control scaling. Add the following code to the head tag to disable page zooming.

<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">

In the above code, viewport means the viewport, width=device-width means the width of the device is the width of the viewport, initial-scale=1.0 means the initial zoom ratio of the page is 1, maximum-scale=1.0 Indicates that the maximum zoom ratio of the page is also 1, user-scalable=no means that the user cannot zoom the page.

The advantages of this method are that it is simple and easy to use, has a small amount of code, and has good browser compatibility. But this method has a flaw: users can still zoom in and out of the page through a two-finger pinch gesture. Although the ratio range is limited to 1~1, this may still affect the user experience.

The second method is to use JavaScript to monitor zoom events and immediately restore the page zoom ratio to 1 once the user performs a zoom operation. Below is a sample code implemented using jQuery.

$(document).ready(function() {
   $(document).on('touchmove', function(e) {
     if (e.originalEvent.scale !== 1) {
        e.preventDefault();
     }
   });
});

In the above code, we use jQuery to bind a touchmove event. When the user performs the pinch-to-zoom zoom gesture, it is judged whether the zoom ratio is equal to 1. If it is not equal to 1, the preventDefault() method The default behavior for this event is disabled. This effectively prevents users from zooming the page.

It should be noted that this method can only disable gesture zooming. If the user uses shortcut keys or the zoom option in the browser menu bar to zoom in and out of the page, this method will be invalid.

The third method is to use both meta tags and JavaScript to monitor scaling events. This method combines the advantages of the first two methods and is more complex in implementation, but it can also achieve better results. The following is a sample code:

<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">

var prevScale = 1;
$(document).ready(function() {
    $(document).on('touchmove', function(e) {
        if (e.originalEvent.scale !== prevScale) {
            $('meta[name=viewport]').attr('content', 'width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no');
        }
        prevScale = e.originalEvent.scale;
    });
});

Explain the function of the above code:

In the first step, we use the meta tag to prohibit users from zooming the page.

The second step is to use JavaScript to listen to the touchmove event.

The third step is to check whether the e.originalEvent.scale value is equal to prevScale. If not, reset the content of the meta tag and disable page scaling.

It should be noted that this method also has flaws. Zooming cannot be completely disabled, and some unexpected situations may still occur.

In short, in some scenarios, it is a common requirement to prohibit users from zooming in on web pages. We can choose a suitable method to achieve this purpose and improve the experience of web pages on mobile devices.

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