22 lines
545 B
Markdown
22 lines
545 B
Markdown
---
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title: Value is async function
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tags: type,function
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expertise: intermediate
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firstSeen: 2020-08-07T15:41:55+03:00
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lastUpdated: 2020-10-20T11:21:07+03:00
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---
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Checks if the given argument is an `async` function.
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- Use `Object.prototype.toString()` and `Function.prototype.call()` and check if the result is `'[object AsyncFunction]'`.
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```js
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const isAsyncFunction = val =>
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Object.prototype.toString.call(val) === '[object AsyncFunction]';
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```
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```js
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isAsyncFunction(function() {}); // false
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isAsyncFunction(async function() {}); // true
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```
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