Ideally the iframe content/functionality would be built in Webflow. But if you can't do that and need it to be an iframe, then it should be loaded in the following way:
- Using a facade to prevent the iframe from loading immediately, blocking the page from rendering. Then after the page is done rendering, the facade (could be an image, loader, etc) can be replaced with the iframe. This method requires custom code.
- Assign dimensions to the iframe to ensure there is no page movement/layout shifts when inserting the iframe after page load
- If the iframe is not above the fold, consider lazy loading it or use the same facade approach mentioned above but load it when scrolled into view
- Ensure content in the iframe is optimized. It's possible for content within to slow things down and affect the user experience i.e., nested iframes
Accessibility considerations:
- Use the title attribute on the iframe for users on assistive devices. More on attributes for accessibility with iframes here.
- Ensure content in the iframe is accessible i.e., semantic html, relevant aria labels, alt text for images, etc. Consider using other attributes that are relevant
- Consider providing a link to the iframe in the event it is not accessible.
- Ensure keyboard focus can move in/out of the iframe.
- Ensure mobile responsiveness and try to match with native website for a smoother user experience.
- Explore usage of the sandbox attribute for security.