allowfullscreen

an HTML attribute for the iframe tag

What's the syntax for allowfullscreen in HTML5?

Answers:

In HTML5, the allowfullscreen attribute is used as a Boolean attribute for the <iframe> element. When this attribute is present, it indicates that the iframe can be displayed in full-screen mode. The syntax for using allowfullscreen is as follows:
```
<iframe src="your-video-url" allowfullscreen></iframe>
```
You can also use the allow attribute to specify more granular permissions, including full-screen capabilities. Here’s how you can use the allow attribute together with allowfullscreen:
```
<iframe src="your-video-url" allow="fullscreen" allowfullscreen></iframe>
```
In this case, using allow="fullscreen" more explicitly communicates that full-screen is permitted.

Example of Basic Usage

Here’s a complete example of an iframe that might embed a video from a source that supports full-screen:
```
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Fullscreen Example</title>
</head>
<body>
    <iframe src="https://www.example.com/video" width="640" height="360" allow="fullscreen" allowfullscreen></iframe>
</body>
</html>
```
In this example, the embedded content from "example.com/video" can be viewed in full-screen mode.

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