Here’s a breakdown of the HTML code provided, focusing on the image and its responsive behavior:
Overall Structure
The code snippet represents an image within a larger HTML structure (likely a news article or blog post). It uses the element to provide a responsive image experience.Key Elements
: This element is the core of the responsive image setup. It allows you to specify different image sources based on media queries (screen size, resolution, etc.).
: These elements define the different image sources. type="image/webp": Specifies that the image is in WebP format (a modern image format that offers better compression than JPEG or PNG).
media="(max-width: 40em)": This is a media query. It means that the browser will use this if the screen width is 40em or less. (1em is typically equal to the current font size, so 40em is roughly 640 pixels if the default font size is 16px).
srcset="...": This attribute lists the different image URLs and their widths. The browser will choose the most appropriate image based on the screen size and pixel density. For example:
https://images.ndr.de/image/.../friedland-118.webp?width=256 256w means there’s a WebP image at that URL that is 256 pixels wide.
The w unit indicates the width of the image.
sizes="1px": this attribute is crucial for the browser to calculate the correct image to download. In this case,sizes="1px" is unusual and likely a placeholder or an error. It tells the browser to assume the image will always take up 1 pixel of space, which is not realistic. A more appropriate value would be something like sizes="(max-width: 600px) 100vw, 50vw" which would tell the browser to use 100% of the viewport width on smaller screens and 50% on larger screens.
: This is the fallback image. If the browser doesn’t support WebP or the media queries don’t match, it will display this image.
src="https://images.ndr.de/image/.../friedland-118.webp?width=576": The URL of the fallback image. alt="A photo of the dead 16-year-olds stands with a candle and a red rose at Friedland train station.": Provides alternative text for accessibility (screen readers) and if the image fails to load.
title="A photo of the dead 16-year-olds stands with a candle and a red rose at Friedland train station. | NDR screenshot": Provides a tooltip when the user hovers over the image.
class="responsive": Likely a CSS class that applies responsive styling to the image (e.g., making it scale to fit its container).
loading="lazy": Tells the browser to lazy-load the image, meaning it won’t be loaded until it’s near the viewport. This improves page load performance.
How it Works (Responsive Images)
- Browser Check: The browser checks if it supports WebP images.
- Media Query Evaluation: The browser evaluates the
mediaattribute of eachelement to see if it matches the current screen size. - Image Selection: if a
matches, the browser selects the image from thesrcsetattribute that best fits the screen size and pixel density. It tries to choose the image that is closest in size to the actual display size to avoid needless downloading of large images. - fallback: If no
matches or the browser doesn’t support WebP, it falls back to theelement.
Issues and Improvements
* sizes="1px": This is a major issue.
