iframe is an inline framework used in HTML to embed external content, suitable for embedding third-party content such as maps, videos, and advertisements; 1. Pay attention to security, style adaptation and loading performance when using it; 2. The basic writing method is , which can set size, full-screen playback and other functions; 3. Optimization includes removing borders, realizing responsive layouts, and using lazy loading to improve performance; 4. In terms of security, sandbox and allow attributes should be used to limit iframe behavior to prevent potential attacks; mastering these key points can ensure that iframes are stable and securely integrated into the web page.

Let me directly talk about the key points: embedding external content with HTML <iframe></iframe> tags is actually quite simple, but if you want to use them well, you have to pay attention to several key points, such as security, style adaptation and loading performance.

What is an iframe? What is suitable for?

<iframe></iframe> means "inline frame", which can embed another web page in the current web page. Commonly used to embed maps, videos, advertisements, third-party gadgets and other content.

For example, if you see an embedded YouTube video on a web page, or displaying the location of Google Maps, many of them use iframes.

Its advantages are:

• No need to write your own code to achieve complex functions
• Content is maintained by a third party, which saves trouble
• Loading is independent and will not easily affect the performance of the main page (although there are exceptions)

Basic usage method

The most basic way to write is very simple:

 <iframe src="https://example.com" width="100%" height="500"></iframe>

where src is the content address you want to embed, and width and height control the display area size.

You can set it as needed:

• Use percentage or fixed pixel values ??to control size
• Add allowfullscreen attribute to allow full screen to play video
• Set allow="autoplay" to allow automatic playback (but this is often restricted by the browser)

It should be noted that some websites will prevent them from being embedded in iframes (such as some news websites), and you will see blanks or error messages at this time.

How to make iframes better integrate into the page?

The default iframe is a block-level element, but sometimes you will find that it is not very harmonious with the layout of the surrounding content, or it may interfere with the visual effects such as borders and scroll bars.

Common optimization methods include:

• Remove the default border : add frameborder="0" or use CSS to set border: none;
• Responsive design : wrap an iframe with CSS so that it can adapt to different screen widths, for example:

 <div style="position: relative; padding-bottom: 56.25%;">
  <iframe src="..." style="position: absolute; width: 100%; height: 100%; border: none;"></iframe>
</div>

This code will keep the iframe at a 16:9 ratio and it can be displayed normally on different devices.

• Consider loading performance : If the page has many iframes, it may slow down the overall loading speed. You can use lazy loading attribute loading="lazy" to improve the experience:

 <iframe src="..." loading="lazy"></iframe>

Don't ignore security issues

Although iframes are very convenient, they may also bring security risks, such as clickjacking attacks.

For more security, it is recommended to add the following attributes:

• sandbox : Restrict the behavior of content in iframes, such as prohibiting pop-ups, script execution, etc.
• allow property: explicitly allows certain behaviors, such as camera access, full-screen playback, etc.

For example:

 <iframe src="..." sandbox="allow-same-origin allow-scripts allow-popups"></iframe>

This not only ensures that the basic functions are available, but also avoids some potential risks.

Basically that's it. Embedding content with an iframe is not complicated, but it is easy to cause problems if the details are not done well. If you master these key points, you can use them more safely.

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