`Promise.race()`

Settles as soon as the first input promise settles, fulfilled or rejected.

Since ES2015 (ES6) Spec ↗

Syntax

Promise.race(iterable)

Returns

Promise — A promise that adopts the state of the first promise to settle.

Examples

const fast = new Promise(r => setTimeout(() => r("fast"), 10));
const slow = new Promise(r => setTimeout(() => r("slow"), 50));
Promise.race([fast, slow]).then(v => console.log(v));

Output

fast

Promise.race([
  Promise.reject(new Error("first")),
  Promise.resolve("second"),
]).catch(e => console.log(e.message));

Output

first

Notes

- The first promise to settle wins, whether it fulfills or rejects. - Commonly used to implement timeouts against a slow operation. - With an empty iterable the returned promise never settles.

Browser & runtime support

Environment	Since version
chrome	`32`
firefox	`29`
safari	`8`
edge	`12`
node	`0.12`