26 lines
693 B
Markdown
26 lines
693 B
Markdown
---
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title: isWritableStream
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tags: node,type,intermediate
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---
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Checks if the given argument is a writable stream.
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- Check if the value is different from `null`.
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- Use `typeof` to check if the value is of type `object` and the `pipe` property is of type `function`.
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- Additionally check if the `typeof` the `_write` and `_writableState` properties are `function` and `object` respectively.
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```js
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const isWritableStream = val =>
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val !== null &&
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typeof val === 'object' &&
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typeof val.pipe === 'function' &&
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typeof val._write === 'function' &&
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typeof val._writableState === 'object';
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```
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```js
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const fs = require('fs');
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isWritableStream(fs.createWriteStream('test.txt')); // true
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```
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