name : string_decoder.md # String decoder <!--introduced_in=v0.10.0--> > Stability: 2 - Stable <!-- source_link=lib/string_decoder.js --> The `node: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('node:string_decoder'); ``` The following example shows the basic use of the `StringDecoder` class. ```js const { StringDecoder } = require('node:string_decoder'); const decoder = new StringDecoder('utf8'); const cent = Buffer.from([0xC2, 0xA2]); console.log(decoder.write(cent)); // Prints: ¢ const euro = Buffer.from([0xE2, 0x82, 0xAC]); console.log(decoder.write(euro)); // Prints: € ``` 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('node:string_decoder'); const decoder = new StringDecoder('utf8'); decoder.write(Buffer.from([0xE2])); decoder.write(Buffer.from([0x82])); console.log(decoder.end(Buffer.from([0xAC]))); // Prints: € ``` ## Class: `StringDecoder` ### `new StringDecoder([encoding])` <!-- YAML added: v0.1.99 --> * `encoding` {string} The character [encoding][] the `StringDecoder` will use. **Default:** `'utf8'`. Creates a new `StringDecoder` instance. ### `stringDecoder.end([buffer])` <!-- YAML added: v0.9.3 --> * `buffer` {string|Buffer|TypedArray|DataView} 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. After `end()` is called, the `stringDecoder` object can be reused for new input. ### `stringDecoder.write(buffer)` <!-- YAML added: v0.1.99 changes: - version: v8.0.0 pr-url: https://github.com/nodejs/node/pull/9618 description: Each invalid character is now replaced by a single replacement character instead of one for each individual byte. --> * `buffer` {string|Buffer|TypedArray|DataView} 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()`. [encoding]: buffer.md#buffers-and-character-encodings