What is an Iframe?

An iframe is also known as Inline Frame. It can be used to include another page in your page. This will yield a small frame that shows the exact contents of the base.html.

<h2 style="text-align:center">In this Iframe we embed The Pro Developer Website</h2>

<iframe src="https://blog.theprodevelopers.com/" width="100%" height="300px"></iframe>

<h2 style="text-align:center">In this Iframe we embed a HTML webpage </h2>

<iframe src="iframe-example.html" width="100%" height="300px"></iframe>

Sandboxing

The following embeds an untrusted web page with all restrictions enabled

<iframe sandbox src="http://example.com/"></iframe>

To allow the page to run scripts and submit forms, add allow-scripts and allow-forms to the sandbox attribute.

<iframe sandbox="allow-scripts allow-forms" src="http://example.com/"></iframe>

If there is untrusted content (such as user comments) on the same domain as the parent web page, an iframe can be used to disable scripts while still allowing the parent document to interact with its content using JavaScript.

<iframe sandbox="allow-same-origin allow-top-navigation"

src="http://example.com/untrusted/comments/page2">

The parent document can add event listeners and resize the IFrame to fit its contents. This, along with allow-topnavigation, can make the sandboxed iframe appear to be part of the parent document.

Note: This sandbox is not a replacement for sanitizing input but can be used as part of a defense in-depth strategy.

Also, be aware that this sandbox can be subverted by an attacker convincing a user to visit the iframe's source directly. The Content Security Policy HTTP header can be used to mitigate this attack.

Setting the Frame Size

The IFrame can be resized using the width and height attributes, where the values are represented in pixels (HTML 4.01 allowed percentage values, but HTML 5 only allows values in CSS pixels).

<iframe src="https://blog.theprodevelopers.com" width="800" height="600"></iframe>

Using of "srcdoc" Attribute

The srcdoc attribute can be used (instead of the src attribute) to specify the exact contents of the iframe as a whole HTML document. This will yield an IFrame with the text "IFrames are cool!"

<iframe srcdoc="<p>Hi i am paragraph and you can directly change Inner HTML of Iframe using srcdoc</p>"></iframe>

If the srcdoc attribute isn't supported by the browser, the IFrame will instead fall back to using the src attribute, but if both the src and srcdoc attributes are present and supported by the browser, srcdoc takes precedence.

Example:

<iframe srcdoc="<p>Iframe is Cool!</p>" src="https://blog.theprodevelopers.com"></iframe>

In the above example, if the browser does not support the srcdoc attribute, it will instead display the contents of the blog.theprodevelopers.com page

Using Anchors with IFrames

Normally a change of webpage within an Iframe is initiated from with the Iframe, for example, clicking a link inside the Ifame. However, it is possible to change an IFrame's content from outside the IFrame. You can use an anchor tag whose href attribute is set to the desired URL and whose target attribute is set to the iframe's name attribute

<iframe src="iframe-example.html" name="myIframe" width="100%" height="200"></iframe><br>

<a href="https://blog.theprodevelopers.com" target="myIframe">Change the Iframe content to The Pro Developer website</a>