22 lines
615 B
Markdown
22 lines
615 B
Markdown
---
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title: runPromisesInSeries
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tags: function,promise,intermediate
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firstSeen: 2017-12-17T17:55:51+02:00
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lastUpdated: 2020-10-22T20:24:30+03:00
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---
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Runs an array of promises in series.
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- Use `Array.prototype.reduce()` to create a promise chain, where each promise returns the next promise when resolved.
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```js
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const runPromisesInSeries = ps =>
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ps.reduce((p, next) => p.then(next), Promise.resolve());
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```
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```js
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const delay = d => new Promise(r => setTimeout(r, d));
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runPromisesInSeries([() => delay(1000), () => delay(2000)]);
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// Executes each promise sequentially, taking a total of 3 seconds to complete
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```
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