Nodejs Study notes (based on v7.4.0)

Nodejs Study Notes

First, buffer:

Global Objects (Singleton buffer.from buffer.alloc Buffer.allocunsafe)

Encoding type	Describe
Ascii	Only for 7-bit ascall data encoding, fast, if set up will peel the high
Utf8	Multibyte-encoded Unicode characters, which most of the Web page's documents default to.
Utf16le	Small-end encoded Unicode characters, 2 or 4 bytes
Ucs2	Aliases for Utf16le
Base64	Base64 is one of the most common encoding methods for transmitting 8Bit bytes of code on the network
Latin1	One way to encode buffer as a byte encoded string, same as binary
Binary	Aliases for Latin1
Hex	Encode each byte as two hexadecimal characters

Method parameters	Describe	Precautions
Buffer.from (Array)	Array normal arrays Returns a new buffer containing a copy of the provided eight-bit byte	Note that the array must be a number, and if it is a string, it will return a buffer equivalent to the length of the array initialized to 0 (see Example 1)
Buffer.from (arraybuffer[, Byteoffset [, length]])	1, ArrayBuffer: Inherit Typedarry or ArrayBuffer. Buffer 2, Byteoffset: Start copy of the cursor, the default starting from 0 3, Length: To be copied, the default Arraybuffer.length-byteoffset Returns a new buffer that shares the same allocated memory as the given Arraybuffer	Note: Shared memory, like the shallow copy of JS, shared memory, a change will change (see Example 2)
Buffer.from (buffer)	Buffer: The existing buffer used to copy data from Returns a new buffer containing a copy of the contents of the given buffer	Note: Each has a different memory (see example 3)
Buffer.from (string[, encoding])	String: Strings to encode Encoding: Encoding format Returns a new buffer containing a copy of the supplied string	(see Example 4)

Example 1:

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Example 2:

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Example 3

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Example 4:

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Method parameters	Describe	Precautions
Buffer.alloc (size[, fill[, encoding])	Size: Sizes of new buffer Fill: Initialized data Encoding: Encoding format Returns the new buffer	Compared to Allocunsafe, it is slower but ensures that no dirty data or initialized data is available (see example 5)
Buffer.allocunsafe (size)	Size: Sizes of new buffer Returns a new buffer that shares the same allocated memory as the given Arraybuffer	Compared to alloc, it is faster, but with dirty data and does not initialize (see example 5)

Case 5:

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This article is from the "Do Your torrent" blog, please be sure to keep this source http://blackrain.blog.51cto.com/10622094/1891864

Nodejs Study notes (based on v7.4.0)