Advent of Svelte 2025 - Day 20: Out of Order Streaming #javascript #sveltejs #webdevelopment

Description

One of the best features from Svelte's new async system! When you have sibling components with async operations, Svelte's compiler is smart enough to fire them all off simultaneously instead of blocking. A component waiting 1 second, another waiting 2 seconds, and a third also waiting 2 seconds? They all resolve in just 2 seconds total. This works through your entire component tree, not just siblings — parent and child async operations run in parallel too. Add a svelte:boundary with a loading state and each component streams in independently the moment its data arrives. Combined with Remote Functions, building fast, responsive UIs has never been easier. Read more: https://svelte.dev/docs/svelte/await-expressions