HTML i-frame

 The <iframe> (inline frame) tag in HTML is used to embed another HTML document within the current document. It allows you to display external content such as web pages, videos, or even other HTML documents inside a frame.

Here’s a detailed explanation of the <iframe> tag and its attributes:


Basic Syntax:

<iframe src="url" width="600" height="400"></iframe>
  • src: Specifies the URL of the page to display inside the iframe.
  • width and height: Define the size of the iframe.

Attributes of <iframe>

Attribute

Description

Possible Values

Default

src

Specifies the URL of the page to be embedded within the iframe.

A valid URL (e.g., https://example.com)

None (Required)

width

Defines the width of the iframe.

Pixel values (e.g., 600px) or percentage (50%)

300px (if unspecified)

height

Defines the height of the iframe.

Pixel values (e.g., 400px) or percentage (50%)

150px (if unspecified)

name

Assigns a name to the iframe, which can be targeted by links or forms.

A string (e.g., myiframe)

None

sandbox

Enables an extra set of restrictions for the content in the iframe for enhanced security.

Empty (restricts all features), or a space-separated list of values (e.g., allow-forms allow-scripts)

None

allow

Specifies which features the iframe is allowed to use (e.g., camera, microphone, fullscreen).

A space-separated list (e.g., fullscreen, camera)

None

srcdoc

Specifies the HTML content to be displayed inside the iframe, instead of a URL.

HTML code (e.g., <h1>Embedded content</h1>)

None

frameborder

Controls whether the iframe should have a border around it.

0 (no border), 1 (border visible)

1 (default)

allowfullscreen

Allows the iframe content to be displayed in fullscreen mode.

true or false

None

loading

Specifies when the iframe content should be loaded.

lazy, eager

eager (default)

referrerpolicy

Controls the referrer information sent when navigating inside the iframe.

no-referrer, origin, unsafe-url, etc.

no-referrer

title

Provides a title for the iframe, improving accessibility and SEO.

A string (e.g., Google Search)

None

longdesc

Specifies a link to a detailed description of the content inside the iframe.

A URL (e.g., longdesc="description.html")

None


Examples

1. Basic Iframe with External Content

<iframe src="https://www.example.com" width="600" height="400"></iframe>

2. Iframe with Name (for Form Targeting)

<iframe name="myiframe" src="https://www.example.com" width="600" height="400"></iframe>

You can target this iframe with a form:

<form target="myiframe">
  <input type="text" name="username" />
  <input type="submit" value="Submit" />
</form>

3. Iframe with Sandbox Restrictions

<iframe src="https://www.example.com" width="600" height="400" sandbox="allow-scripts allow-forms"></iframe>

This allows only scripts and forms to run inside the iframe, but blocks everything else (e.g., top-level navigation).

4. Iframe with a Custom srcdoc Content

<iframe srcdoc="<h1>Welcome to My Page</h1><p>This is embedded content.</p>" width="600" height="400"></iframe>

The srcdoc attribute allows you to specify HTML content directly within the iframe.

5. Iframe with Lazy Loading

<iframe src="https://www.example.com" width="600" height="400" loading="lazy"></iframe>

This will load the iframe content only when it's about to enter the viewport, which can improve page load times.

6. Iframe with Fullscreen Capability

<iframe src="https://www.youtube.com" width="600" height="400" allowfullscreen></iframe>

This will allow the content (e.g., video) to be displayed in fullscreen mode.

7. Iframe with Referrer Policy

<iframe src="https://www.example.com" width="600" height="400" referrerpolicy="no-referrer"></iframe>

This prevents the iframe from sending any referrer information when navigating within the iframe.


Security Considerations

  • Sandboxing: The sandbox attribute is particularly important for security. It limits the capabilities of the iframe content, which can help prevent malicious actions like script execution and form submissions.
    • Possible values for sandbox:
      • allow-scripts: Allows JavaScript to run.
      • allow-forms: Allows form submission.
      • allow-same-origin: Allows the iframe content to be treated as being from the same origin.
      • allow-popups: Allows popups to be opened.
      • allow-top-navigation: Allows the iframe to navigate the top-level browsing context (the parent page).
      • A blank sandbox attribute will block all features unless explicitly allowed.

Iframe Accessibility

  • title: Always provide a title attribute for iframes to improve accessibility, as screen readers use it to describe the content inside the iframe.

  • longdesc: You can use the longdesc attribute to link to a detailed description of the iframe content, especially useful for accessibility purposes.

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