srcsetattribuuteilla

The srcset attribute is a powerful HTML attribute used with the img element to provide a set of image sources for the browser to choose from. This allows for responsive image delivery, meaning the browser can select the most appropriate image based on factors like screen resolution, pixel density, and viewport size.

When using srcset, you provide a comma-separated list of image URLs, each followed by a descriptor. These descriptors indicate the conditions under which that particular image should be used. There are two main types of descriptors: width descriptors (e.g., 1000w) and pixel density descriptors (e.g., 2x).

A width descriptor tells the browser the intrinsic width of the image file in pixels. For example, "image-small.jpg 400w, image-large.jpg 800w" suggests that image-small.jpg is 400 pixels wide and image-large.jpg is 800 pixels wide. The browser then uses the layout viewport width and these descriptors to pick the best image.

Pixel density descriptors are used to serve higher-resolution images to devices with higher pixel densities. For instance, "image.jpg 1x, image-2x.jpg 2x" would tell the browser to use image.jpg for standard displays and image-2x.jpg for displays with twice the pixel density.

The browser automatically handles the selection process based on the information provided in srcset, ensuring users download only the most suitable image, which can significantly improve page load times and user experience, especially on mobile devices. It is often used in conjunction with the sizes attribute to give the browser more context about how the image will be displayed within the layout.