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Clear filtersSemantic elements describe their meaning in the name, such as header, nav, main, article and footer, so browsers, assistive technology and search engines can understand the page structure.
Cookies are sent to the server with every matching request and can expire; localStorage persists until cleared and stays in the browser; sessionStorage lasts for the current tab only.
Event delegation means attaching one listener to a parent element and using event bubbling to handle events from its children, instead of adding a listener to each child.
The event loop is the mechanism that lets single-threaded JavaScript handle asynchronous work: it runs the call stack to empty, then runs all queued microtasks (promises), then takes the next task (timers, events) from the queue.
Debounce waits until the user stops triggering an event for a set time before running the function; throttle runs the function at most once per time interval no matter how often the event fires.
Both download the script without blocking HTML parsing. defer waits until parsing finishes and runs scripts in document order; async runs a script as soon as it is downloaded, which can be before or after parsing and in any order.
The browser parses HTML into a DOM and CSS into a CSSOM, combines them into a render tree, computes layout (reflow), paints pixels and composites layers onto the screen.