Promises and async functions
A Promise represents eventual completion or failure. An async function returns a Promise, and await pauses that function until a value settles.
What it is
A Promise represents eventual completion or failure. An async function returns a Promise, and await pauses that function until a value settles.
Why it matters
Await does not move CPU work to another thread. A long synchronous loop still blocks interaction.
Example
Awaiting fetch lets other work run while data arrives; parsing a huge JSON string afterward still uses the current thread.
Technical detail
A rejected promise must be handled through await with try/catch or a rejection handler.
When to use it
Start independent requests together, then await their results. Keep dependent mutations in the required order.
Sources
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Assembled from the ReLU.chat curated knowledge base. These explanations are concise on purpose; check the sources for anything important.