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doc: general improvements to string_decoder.md copy

PR-URL: https://github.com/nodejs/node/pull/6940
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Brian White <mscdex@mscdex.net>
v7.x
James M Snell 9 years ago
parent
commit
9140b97848
  1. 56
      doc/api/string_decoder.md

56
doc/api/string_decoder.md

@ -2,9 +2,15 @@
Stability: 2 - Stable
To use this module, do `require('string_decoder')`. StringDecoder decodes a
buffer to a string. It is a simple interface to `buffer.toString()` but provides
additional support for utf8.
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:
```js
const StringDecoder = require('string_decoder').StringDecoder;
```
The following example shows the basic use of the `StringDecoder` class.
```js
const StringDecoder = require('string_decoder').StringDecoder;
@ -17,23 +23,55 @@ const euro = Buffer.from([0xE2, 0x82, 0xAC]);
console.log(decoder.write(euro));
```
## Class: StringDecoder
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:
```js
const StringDecoder = require('string_decoder').StringDecoder;
const decoder = new StringDecoder('utf8');
decoder.write(Buffer.from([0xE2]));
decoder.write(Buffer.from([0x82]));
console.log(decoder.end(Buffer.from([0xAC])));
```
## Class: new StringDecoder([encoding])
<!-- YAML
added: v0.1.99
-->
Accepts a single argument, `encoding` which defaults to `'utf8'`.
* `encoding` {string} The character encoding the `StringDecoder` will use.
Defaults to `'utf8'`.
### decoder.end()
Creates a new `StringDecoder` instance.
### stringDecoder.end([buffer])
<!-- YAML
added: v0.9.3
-->
Returns any trailing bytes that were left in the buffer.
* `buffer` {Buffer} A `Buffer` containing the bytes to decode.
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.
### decoder.write(buffer)
If the `buffer` argument is provided, one final call to `stringDecoder.write()`
is performed before returning the remaining input.
### stringDecoder.write(buffer)
<!-- YAML
added: v0.1.99
-->
Returns a decoded string.
* `buffer` {Buffer} A `Buffer` containing the bytes to decode.
Returns a decoded string, ensuring that any incomplete multibyte characters at
the end of the `Buffer` are omitted from the returned string and stored in an
internal buffer for the next call to `stringDecoder.write()` or
`stringDecoder.end()`.

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