HTMLImageElement.prototype.src Setter
This is a sophisticated programming technique used by Speed Kit's algorithm to accurately measure the Largest Contentful Paint (LCP) on complex, JavaScript-heavy sites. It allows Speed Kit to intercept and know the exact moment a script assigns a source URL to an image tag. This is crucial for identifying the true LCP element and its load time when the main image is loaded dynamically by JavaScript rather than being present in the initial HTML.
Related web performance terms
- HAR
A HAR (HTTP Archive format) file is a JSON-formatted log of a web browser's interaction with a site. It contains a detailed, timestamped record of every single network request and response, includi…
- HTML Size
The amount of data (in bytes) that comprises the HTML document sent from the server to the browser. This includes the HTML markup but excludes CSS, JavaScript, images, and other resources.
- HTTP/2
HTTP/2 is a major version of the HTTP protocol designed to make websites faster and more efficient. Its key feature is multiplexing, which allows a browser to download multiple resources (like CSS…
- HTTP/3
HTTP/3 is the latest version of the HTTP protocol, engineered for even greater performance, especially on unreliable networks. It is built on a new transport protocol called QUIC instead of TCP.