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JavaScriptAdvanced#async#promises
JavaScriptIntermediate#async#promises
What is a Promise and what are its states?
A Promise is an object representing the eventual result of an async operation, in state pending, fulfilled or rejected. It settles once and then notifies then/catch/finally handlers.
Example
const p = new Promise((resolve, reject) => {
setTimeout(() => resolve('done'), 100);
});
p.then(v => console.log(v)).catch(console.error).finally(() => console.log('cleanup'));