39 lines
706 B
Markdown
39 lines
706 B
Markdown
---
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title: chainAsync
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tags: function,intermediate
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firstSeen: 2017-12-17T17:55:51+02:00
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lastUpdated: 2020-09-15T16:28:04+03:00
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---
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Chains asynchronous functions.
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- Loop through an array of functions containing asynchronous events, calling `next` when each asynchronous event has completed.
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```js
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const chainAsync = fns => {
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let curr = 0;
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const last = fns[fns.length - 1];
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const next = () => {
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const fn = fns[curr++];
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fn === last ? fn() : fn(next);
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};
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next();
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};
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```
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```js
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chainAsync([
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next => {
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console.log('0 seconds');
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setTimeout(next, 1000);
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},
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next => {
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console.log('1 second');
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setTimeout(next, 1000);
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},
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() => {
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console.log('2 second');
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}
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]);
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```
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