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doc: copyedit buffer doc

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PR-URL: https://github.com/nodejs/node/pull/4187
Reviewed-By: Michaël Zasso <mic.besace@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
This commit is contained in:
Rich Trott 2015-12-07 19:21:24 -08:00
parent 70fb06a90b
commit e47ae5808b
1 changed files with 38 additions and 38 deletions
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doc/api/buffer.markdown
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@ -2,7 +2,7 @@
Stability: 2 - Stable Stability: 2 - Stable
Pure JavaScript is Unicode friendly but not nice to binary data. When Pure JavaScript is Unicode-friendly but not nice to binary data. When
dealing with TCP streams or the file system, it's necessary to handle octet dealing with TCP streams or the file system, it's necessary to handle octet
streams. Node.js has several strategies for manipulating, creating, and streams. Node.js has several strategies for manipulating, creating, and
consuming octet streams. consuming octet streams.
@ -15,23 +15,23 @@ The `Buffer` class is a global, making it very rare that one would need
to ever `require('buffer')`. to ever `require('buffer')`.
Converting between Buffers and JavaScript string objects requires an explicit Converting between Buffers and JavaScript string objects requires an explicit
encoding method. Here are the different string encodings. encoding method. The different string encodings are:
* `'ascii'` - for 7 bit ASCII data only. This encoding method is very fast, and * `'ascii'` - for 7-bit ASCII data only. This encoding method is very fast and
will strip the high bit if set. will strip the high bit if set.
* `'utf8'` - Multibyte encoded Unicode characters. Many web pages and other * `'utf8'` - Multibyte encoded Unicode characters. Many web pages and other
document formats use UTF-8. document formats use UTF-8.
* `'utf16le'` - 2 or 4 bytes, little endian encoded Unicode characters. * `'utf16le'` - 2 or 4 bytes, little-endian encoded Unicode characters.
Surrogate pairs (U+10000 to U+10FFFF) are supported. Surrogate pairs (U+10000 to U+10FFFF) are supported.
* `'ucs2'` - Alias of `'utf16le'`. * `'ucs2'` - Alias of `'utf16le'`.
* `'base64'` - Base64 string encoding. * `'base64'` - Base64 string encoding.
* `'binary'` - A way of encoding the buffer into a one-byte (i.e. `latin-1`) * `'binary'` - A way of encoding the buffer into a one-byte (`latin-1`)
encoded string. The string `'latin-1'` is not supported. Instead simply pass encoded string. The string `'latin-1'` is not supported. Instead, pass
`'binary'` to use `'latin-1'` encoding. `'binary'` to use `'latin-1'` encoding.
* `'hex'` - Encode each byte as two hexadecimal characters. * `'hex'` - Encode each byte as two hexadecimal characters.
@ -45,8 +45,8 @@ Creating a typed array from a `Buffer` works with the following caveats:
with elements `[1,2,3,4]`, not a `Uint32Array` with a single element with elements `[1,2,3,4]`, not a `Uint32Array` with a single element
`[0x1020304]` or `[0x4030201]`. `[0x1020304]` or `[0x4030201]`.
NOTE: Node.js v0.8 simply retained a reference to the buffer in `array.buffer` NOTE: Node.js v0.8 retained a reference to the buffer in `array.buffer` instead
instead of cloning it. of cloning it.
While more efficient, it introduces subtle incompatibilities with the typed While more efficient, it introduces subtle incompatibilities with the typed
arrays specification. `ArrayBuffer#slice()` makes a copy of the slice while arrays specification. `ArrayBuffer#slice()` makes a copy of the slice while
@ -74,9 +74,9 @@ Copies the passed `buffer` data onto a new `Buffer` instance.
* `size` Number * `size` Number
Allocates a new buffer of `size` bytes. `size` must be less than Allocates a new buffer of `size` bytes. `size` must be less than
1,073,741,824 bytes (1 GB) on 32 bits architectures or 1,073,741,824 bytes (1 GB) on 32-bit architectures or
2,147,483,648 bytes (2 GB) on 64 bits architectures, 2,147,483,648 bytes (2 GB) on 64-bit architectures.
otherwise a [`RangeError`][] is thrown. Otherwise, a [`RangeError`][] is thrown.
Unlike `ArrayBuffers`, the underlying memory for buffers is not initialized. So Unlike `ArrayBuffers`, the underlying memory for buffers is not initialized. So
the contents of a newly created `Buffer` are unknown and could contain the contents of a newly created `Buffer` are unknown and could contain
@ -208,14 +208,14 @@ Example: copy an ASCII string into a buffer, one byte at a time:
// Node.js // Node.js
Returns a boolean of whether `this` and `otherBuffer` have the same Returns a boolean indicating whether `this` and `otherBuffer` have the same
bytes. bytes.
### buf.compare(otherBuffer) ### buf.compare(otherBuffer)
* `otherBuffer` {Buffer} * `otherBuffer` {Buffer}
Returns a number indicating whether `this` comes before or after or is Returns a number indicating whether `this` comes before, after, or is
the same as the `otherBuffer` in sort order. the same as the `otherBuffer` in sort order.
@ -227,7 +227,7 @@ the same as the `otherBuffer` in sort order.
* `sourceEnd` Number, Optional, Default: `buffer.length` * `sourceEnd` Number, Optional, Default: `buffer.length`
Copies data from a region of this buffer to a region in the target buffer even Copies data from a region of this buffer to a region in the target buffer even
if the target memory region overlaps with the source. If `undefined` the if the target memory region overlaps with the source. If `undefined`, the
`targetStart` and `sourceStart` parameters default to `0` while `sourceEnd` `targetStart` and `sourceStart` parameters default to `0` while `sourceEnd`
defaults to `buffer.length`. defaults to `buffer.length`.
@ -326,7 +326,7 @@ use [`buf.slice`][] to create a new buffer.
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
* Return: Number * Return: Number
Reads a 64 bit double from the buffer at the specified offset with specified Reads a 64-bit double from the buffer at the specified offset with specified
endian format. endian format.
Set `noAssert` to true to skip validation of `offset`. This means that `offset` Set `noAssert` to true to skip validation of `offset`. This means that `offset`
@ -356,7 +356,7 @@ Example:
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
* Return: Number * Return: Number
Reads a 32 bit float from the buffer at the specified offset with specified Reads a 32-bit float from the buffer at the specified offset with specified
endian format. endian format.
Set `noAssert` to true to skip validation of `offset`. This means that `offset` Set `noAssert` to true to skip validation of `offset`. This means that `offset`
@ -381,7 +381,7 @@ Example:
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
* Return: Number * Return: Number
Reads a signed 8 bit integer from the buffer at the specified offset. Reads a signed 8-bit integer from the buffer at the specified offset.
Set `noAssert` to true to skip validation of `offset`. This means that `offset` Set `noAssert` to true to skip validation of `offset`. This means that `offset`
may be beyond the end of the buffer. Defaults to `false`. may be beyond the end of the buffer. Defaults to `false`.
@ -396,7 +396,7 @@ complement signed values.
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
* Return: Number * Return: Number
Reads a signed 16 bit integer from the buffer at the specified offset with Reads a signed 16-bit integer from the buffer at the specified offset with
specified endian format. specified endian format.
Set `noAssert` to true to skip validation of `offset`. This means that `offset` Set `noAssert` to true to skip validation of `offset`. This means that `offset`
@ -412,7 +412,7 @@ complement signed values.
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
* Return: Number * Return: Number
Reads a signed 32 bit integer from the buffer at the specified offset with Reads a signed 32-bit integer from the buffer at the specified offset with
specified endian format. specified endian format.
Set `noAssert` to true to skip validation of `offset`. This means that `offset` Set `noAssert` to true to skip validation of `offset`. This means that `offset`
@ -447,7 +447,7 @@ may be beyond the end of the buffer. Defaults to `false`.
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
* Return: Number * Return: Number
Reads an unsigned 8 bit integer from the buffer at the specified offset. Reads an unsigned 8-bit integer from the buffer at the specified offset.
Set `noAssert` to true to skip validation of `offset`. This means that `offset` Set `noAssert` to true to skip validation of `offset`. This means that `offset`
may be beyond the end of the buffer. Defaults to `false`. may be beyond the end of the buffer. Defaults to `false`.
@ -477,7 +477,7 @@ Example:
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
* Return: Number * Return: Number
Reads an unsigned 16 bit integer from the buffer at the specified offset with Reads an unsigned 16-bit integer from the buffer at the specified offset with
specified endian format. specified endian format.
Set `noAssert` to true to skip validation of `offset`. This means that `offset` Set `noAssert` to true to skip validation of `offset`. This means that `offset`
@ -513,7 +513,7 @@ Example:
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
* Return: Number * Return: Number
Reads an unsigned 32 bit integer from the buffer at the specified offset with Reads an unsigned 32-bit integer from the buffer at the specified offset with
specified endian format. specified endian format.
Set `noAssert` to true to skip validation of `offset`. This means that `offset` Set `noAssert` to true to skip validation of `offset`. This means that `offset`
@ -604,7 +604,7 @@ See `buffer.write()` example, above.
### buf.toJSON() ### buf.toJSON()
Returns a JSON-representation of the Buffer instance. `JSON.stringify` Returns a JSON representation of the Buffer instance. `JSON.stringify`
implicitly calls this function when stringifying a Buffer instance. implicitly calls this function when stringifying a Buffer instance.
Example: Example:
@ -650,7 +650,7 @@ The method will not write partial characters.
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian Writes `value` to the buffer at the specified offset with specified endian
format. Note, `value` must be a valid 64 bit double. format. `value` must be a valid 64-bit double.
Set `noAssert` to true to skip validation of `value` and `offset`. This means Set `noAssert` to true to skip validation of `value` and `offset`. This means
that `value` may be too large for the specific function and `offset` may be that `value` may be too large for the specific function and `offset` may be
@ -679,7 +679,7 @@ Example:
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian Writes `value` to the buffer at the specified offset with specified endian
format. Note, behavior is unspecified if `value` is not a 32 bit float. format. Behavior is unspecified if `value` is not a 32-bit float.
Set `noAssert` to true to skip validation of `value` and `offset`. This means Set `noAssert` to true to skip validation of `value` and `offset`. This means
that `value` may be too large for the specific function and `offset` may be that `value` may be too large for the specific function and `offset` may be
@ -706,8 +706,8 @@ Example:
* `offset` Number * `offset` Number
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset. Note, `value` must be a Writes `value` to the buffer at the specified offset. `value` must be a
valid signed 8 bit integer. valid signed 8-bit integer.
Set `noAssert` to true to skip validation of `value` and `offset`. This means Set `noAssert` to true to skip validation of `value` and `offset`. This means
that `value` may be too large for the specific function and `offset` may be that `value` may be too large for the specific function and `offset` may be
@ -725,7 +725,7 @@ signed integer into `buffer`.
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian Writes `value` to the buffer at the specified offset with specified endian
format. Note, `value` must be a valid signed 16 bit integer. format. `value` must be a valid signed 16-bit integer.
Set `noAssert` to true to skip validation of `value` and `offset`. This means Set `noAssert` to true to skip validation of `value` and `offset`. This means
that `value` may be too large for the specific function and `offset` may be that `value` may be too large for the specific function and `offset` may be
@ -743,7 +743,7 @@ complement signed integer into `buffer`.
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian Writes `value` to the buffer at the specified offset with specified endian
format. Note, `value` must be a valid signed 32 bit integer. format. `value` must be a valid signed 32-bit integer.
Set `noAssert` to true to skip validation of `value` and `offset`. This means Set `noAssert` to true to skip validation of `value` and `offset`. This means
that `value` may be too large for the specific function and `offset` may be that `value` may be too large for the specific function and `offset` may be
@ -778,8 +778,8 @@ to `false`.
* `offset` Number * `offset` Number
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset. Note, `value` must be a Writes `value` to the buffer at the specified offset. `value` must be a
valid unsigned 8 bit integer. valid unsigned 8-bit integer.
Set `noAssert` to true to skip validation of `value` and `offset`. This means Set `noAssert` to true to skip validation of `value` and `offset`. This means
that `value` may be too large for the specific function and `offset` may be that `value` may be too large for the specific function and `offset` may be
@ -806,7 +806,7 @@ Example:
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian Writes `value` to the buffer at the specified offset with specified endian
format. Note, `value` must be a valid unsigned 16 bit integer. format. `value` must be a valid unsigned 16-bit integer.
Set `noAssert` to true to skip validation of `value` and `offset`. This means Set `noAssert` to true to skip validation of `value` and `offset`. This means
that `value` may be too large for the specific function and `offset` may be that `value` may be too large for the specific function and `offset` may be
@ -837,7 +837,7 @@ Example:
* `noAssert` Boolean, Optional, Default: false * `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian Writes `value` to the buffer at the specified offset with specified endian
format. Note, `value` must be a valid unsigned 32 bit integer. format. `value` must be a valid unsigned 32-bit integer.
Set `noAssert` to true to skip validation of `value` and `offset`. This means Set `noAssert` to true to skip validation of `value` and `offset`. This means
that `value` may be too large for the specific function and `offset` may be that `value` may be too large for the specific function and `offset` may be
@ -886,7 +886,7 @@ be overridden by user modules. See [`util.inspect()`][] for more details on
`buffer.inspect()` behavior. `buffer.inspect()` behavior.
Note that this is a property on the buffer module returned by Note that this is a property on the buffer module returned by
`require('buffer')`, not on the Buffer global, or a buffer instance. `require('buffer')`, not on the Buffer global or a buffer instance.
## ES6 iteration ## ES6 iteration
@ -901,7 +901,7 @@ Buffers can be iterated over using `for..of` syntax:
// 2 // 2
// 3 // 3
Additionally, `buffer.values()`, `buffer.keys()` and `buffer.entries()` Additionally, the `buffer.values()`, `buffer.keys()`, and `buffer.entries()`
methods can be used to create iterators. methods can be used to create iterators.
## Class: SlowBuffer ## Class: SlowBuffer
@ -914,7 +914,7 @@ larger allocated object. This approach improves both performance and memory
usage since v8 does not need to track and cleanup as many `Persistent` objects. usage since v8 does not need to track and cleanup as many `Persistent` objects.
In the case where a developer may need to retain a small chunk of memory from a In the case where a developer may need to retain a small chunk of memory from a
pool for an indeterminate amount of time it may be appropriate to create an pool for an indeterminate amount of time, it may be appropriate to create an
un-pooled Buffer instance using SlowBuffer and copy out the relevant bits. un-pooled Buffer instance using SlowBuffer and copy out the relevant bits.
// need to keep around a few small chunks of memory // need to keep around a few small chunks of memory
@ -929,8 +929,8 @@ un-pooled Buffer instance using SlowBuffer and copy out the relevant bits.
store.push(sb); store.push(sb);
}); });
Though this should be used sparingly and only be a last resort *after* a developer This should be used only as a last resort *after* a developer has observed
has actively observed undue memory retention in their applications. undue memory retention in their applications.
[`Array#indexOf()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf [`Array#indexOf()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf
[`buf.fill(0)`]: #buffer_buf_fill_value_offset_end [`buf.fill(0)`]: #buffer_buf_fill_value_offset_end