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Node.js v11.0.0-test20180926d6a6df9ece Documentation
Table of Contents
String Decoder#
The string_decoder
module provides an API for decoding Buffer
objects into
strings in a manner that preserves encoded multi-byte UTF-8 and UTF-16
characters. It can be accessed using:
const { StringDecoder } = require('string_decoder');
The following example shows the basic use of the StringDecoder
class.
const { StringDecoder } = require('string_decoder');
const decoder = new StringDecoder('utf8');
const cent = Buffer.from([0xC2, 0xA2]);
console.log(decoder.write(cent));
const euro = Buffer.from([0xE2, 0x82, 0xAC]);
console.log(decoder.write(euro));
When a Buffer
instance is written to the StringDecoder
instance, an
internal buffer is used to ensure that the decoded string does not contain
any incomplete multibyte characters. These are held in the buffer until the
next call to stringDecoder.write()
or until stringDecoder.end()
is called.
In the following example, the three UTF-8 encoded bytes of the European Euro
symbol (€
) are written over three separate operations:
const { StringDecoder } = require('string_decoder');
const decoder = new StringDecoder('utf8');
decoder.write(Buffer.from([0xE2]));
decoder.write(Buffer.from([0x82]));
console.log(decoder.end(Buffer.from([0xAC])));
Class: StringDecoder#
new StringDecoder([encoding])#
encoding
<string> The character encoding theStringDecoder
will use. Default:'utf8'
.
Creates a new StringDecoder
instance.
stringDecoder.end([buffer])#
buffer
<Buffer> | <TypedArray> | <DataView> ABuffer
, orTypedArray
, orDataView
containing the bytes to decode.- Returns: <string>
Returns any remaining input stored in the internal buffer as a string. Bytes representing incomplete UTF-8 and UTF-16 characters will be replaced with substitution characters appropriate for the character encoding.
If the buffer
argument is provided, one final call to stringDecoder.write()
is performed before returning the remaining input.
stringDecoder.write(buffer)#
buffer
<Buffer> | <TypedArray> | <DataView> ABuffer
, orTypedArray
, orDataView
containing the bytes to decode.- Returns: <string>
Returns a decoded string, ensuring that any incomplete multibyte characters at
the end of the Buffer
, or TypedArray
, or DataView
are omitted from the
returned string and stored in an internal buffer for the next call to
stringDecoder.write()
or stringDecoder.end()
.