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doc: buffer.from will return internal pool buffer #24312

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22 changes: 22 additions & 0 deletions doc/api/buffer.md
Original file line number Diff line number Diff line change
Expand Up @@ -788,6 +788,28 @@ const buf = Buffer.from([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]);

A `TypeError` will be thrown if `array` is not an `Array`.

`Buffer.from(array)` may also use the internal `Buffer` pool just like
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[`Buffer.allocUnsafe()`] does.
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```js
const nodeBuffers = Buffer.from([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);

console.log(nodeBuffers.offset);
// prints: 344
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This is not always correct. It may return 0, and any subsequent call will probably increase it.
So it doesn't always print 344.

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// prints: 344
// Prints: 344


// Default Buffer.poolsize is 8192
console.log(Buffer.poolSize);
// prints: 8192
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// prints: 8192
// Prints: 8192


// But you can change it
Buffer.poolSize = 5;
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This could be misleading. Changing Buffer.poolSize does have immediate effect on which buffers would be pooled, but it doesn't immediately change the size of the current pool, it changes the size of the next pool.
It does, however, take immediate effect for determining whether should the buffer be allocated from the pool or not.


const buf = Buffer.from([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);

console.log(buf.offset);
// prints: 0
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// prints: 0
// Prints: 0

```

### Class Method: Buffer.from(arrayBuffer[, byteOffset[, length]])
<!-- YAML
added: v5.10.0
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