Let’s talk about the methods and principles of prohibiting zooming in HTML5

With the popularity of mobile devices and the responsive layout of web design, HTML5, as a new standard language, has gradually replaced the early HTML markup language. In HTML5, there is a very common requirement, which is to disable page scaling. This article will introduce the method and principle of prohibiting scaling in HTML5.

First of all, why is there a need to ban zooming? Usually, the screen size of mobile devices is small. In order to adapt to the user's browsing experience, some websites will adopt responsive design, that is, the layout of the page will be adaptively adjusted according to the size of the screen. In many cases, users' zooming of the page may affect the effect of responsive design, causing page dislocation and affecting the appearance and experience.

So, how to prohibit page zooming in HTML5? First, we need to understand viewport.

What is Viewport?

Viewport refers to the area in the browser used to display web pages, usually including the browser window and the iframe element of the page. In mobile devices, the viewport area is smaller due to the limited screen size.

Viewport Principle

On the traditional PC side, the size of the viewport is fixed, usually the size of the browser window. On mobile devices, the viewport size can be set to be larger or smaller than the device screen, which needs to be set through the meta tag.

The content attribute includes two parameters: width and initial- scale.

• width: Specify the width of the viewport, usually set to the device width (device-width).
• initial-scale: Specifies the scaling ratio of the viewport, usually set to 1, which means it is displayed according to the actual size.

The initial-scale here is what we need to use to achieve page scaling by adjusting the scaling ratio.

Methods to disable scaling

To disable page scaling, we only need to set the values ​​of maximum-scale and minimum-scale to 1 in the meta tag, as shown below:

In this way, regardless of the user Any attempt to zoom the page will be blocked.

In addition, we can also use JavaScript to disable page scaling, as follows:

document.addEventListener('touchstart',function (event){
if(event.touches.length> ;1){

event.preventDefault();

}
});

document.addEventListener('gesturestart', function (event) {
event.preventDefault();
} );

The function of the above code is to prevent the default zoom event when the user uses two fingers to zoom.

Summary

HTML5 prohibits page scaling by setting the maximum-scale and minimum-scale values ​​in the meta tag to 1, or by blocking the default scaling event through JavaScript. These methods can effectively avoid problems caused by page scaling and improve the user's browsing experience.

Note that although these methods can achieve the purpose of prohibiting page scaling, some mobile devices still have some defects, and problems such as page misalignment or incomplete misalignment may occur. Therefore, it is recommended to fully optimize the design and development of web pages in practical applications by combining technologies such as responsive layout.

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