Optimization: Image elements do not have explicit width and height

[rfultz]

Background

Looking to optimize the site's performance and that of the homepage specifically, the Lighthouse tool in Chromium browsers has made some suggestions. Some of these will have repercussions throughout the app so we're going to make them their own tickets.

Recommendation: Image elements do not have explicit width and height

Set an explicit width and height on image elements to reduce layout shifts and improve CLS. details

Overview

We could set default image sizes for all images so browsers could render the page before waiting for images to fully load.

Benefit (the 80 of 80/20)

Medium? Lighthouse lists it medium-high

Effort (the 20 of 80/20)

Probably light

Complications

• Would these default sizes apply for all browser widths? Any complications across devices sizes?

Completion criteria

• Lighthouse is no longer throwing this warning
• Any images that get a new height/width parameter don't break smaller or wider layouts

Related tickets

• Preload key requests
• Remove unused JavaScript
• Remove unused CSS
• Preconnect to required origins
• Eliminate render-blocking resources
• Ensure text remains visible during webfont load
• Reduce the impact of third-party code
• Does not use passive listeners to improve scrolling performance
• Serve static assets with an efficient cache policy
• Minimize main-thread work
• Avoid an excessive DOM size
• Reduce JavaScript execution time
• Avoid enormous network payloads
• [aria-hidden="true"] elements contain focusable descendents
• Elements with an ARIA [role] that require children to contain a specific [role] are missing some or all of those required children
• [aria-*] attributes do not have valid values
• ARIA IDs are not unique
• Lists do not contain only
• elements and script supporting elements (<script> and )
• [user-scalable="no"] is used in the element or the [maximum-scale] attribute is less than 5
• Links to cross-origin destinations are unsafe
• Serves images with low resolution