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<!doctype html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width"> <title>String Decoder | Node.js v10.24.1 Documentation</title> <link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Lato:400,700,400italic"> <link rel="stylesheet" href="assets/style.css"> <link rel="stylesheet" href="assets/sh.css"> <link rel="canonical" href="https://nodejs.org/api/string_decoder.html"> </head> <body class="alt apidoc" id="api-section-string_decoder"> <div id="content" class="clearfix"> <div id="column2" class="interior"> <div id="intro" class="interior"> <a href="/" title="Go back to the home page"> Node.js </a> </div> <ul> <li><a href="documentation.html" class="nav-documentation">About these Docs</a></li> <li><a href="synopsis.html" class="nav-synopsis">Usage & Example</a></li> </ul> <div class="line"></div> <ul> <li><a href="assert.html" class="nav-assert">Assertion Testing</a></li> <li><a href="async_hooks.html" 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</li> </ul> </li> </ul> </div> <div id="apicontent"> <h1>String Decoder<span><a class="mark" href="#string_decoder_string_decoder" id="string_decoder_string_decoder">#</a></span></h1> <p></p><div class="api_stability api_stability_2"><a href="documentation.html#documentation_stability_index">Stability: 2</a> - Stable</div><p></p> <p>The <code>string_decoder</code> module provides an API for decoding <code>Buffer</code> objects into strings in a manner that preserves encoded multi-byte UTF-8 and UTF-16 characters. It can be accessed using:</p> <pre><code class="language-js">const { StringDecoder } = require('string_decoder'); </code></pre> <p>The following example shows the basic use of the <code>StringDecoder</code> class.</p> <pre><code class="language-js">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)); </code></pre> <p>When a <code>Buffer</code> instance is written to the <code>StringDecoder</code> 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 <code>stringDecoder.write()</code> or until <code>stringDecoder.end()</code> is called.</p> <p>In the following example, the three UTF-8 encoded bytes of the European Euro symbol (<code>€</code>) are written over three separate operations:</p> <pre><code class="language-js">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]))); </code></pre> <h2>Class: StringDecoder<span><a class="mark" href="#string_decoder_class_stringdecoder" id="string_decoder_class_stringdecoder">#</a></span></h2> <h3>new StringDecoder([encoding])<span><a class="mark" href="#string_decoder_new_stringdecoder_encoding" id="string_decoder_new_stringdecoder_encoding">#</a></span></h3> <div class="api_metadata"> <span>Added in: v0.1.99</span> </div> <ul> <li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The character encoding the <code>StringDecoder</code> will use. <strong>Default:</strong> <code>'utf8'</code>.</li> </ul> <p>Creates a new <code>StringDecoder</code> instance.</p> <h3>stringDecoder.end([buffer])<span><a class="mark" href="#string_decoder_stringdecoder_end_buffer" id="string_decoder_stringdecoder_end_buffer">#</a></span></h3> <div class="api_metadata"> <span>Added in: v0.9.3</span> </div> <ul> <li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView></a> A <code>Buffer</code>, or <code>TypedArray</code>, or <code>DataView</code> containing the bytes to decode.</li> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>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.</p> <p>If the <code>buffer</code> argument is provided, one final call to <code>stringDecoder.write()</code> is performed before returning the remaining input.</p> <h3>stringDecoder.write(buffer)<span><a class="mark" href="#string_decoder_stringdecoder_write_buffer" id="string_decoder_stringdecoder_write_buffer">#</a></span></h3> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v8.0.0</td> <td><p>Each invalid character is now replaced by a single replacement character instead of one for each individual byte.</p></td></tr> <tr><td>v0.1.99</td> <td><p><span>Added in: v0.1.99</span></p></td></tr> </tbody></table> </details> </div> <ul> <li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView></a> A <code>Buffer</code>, or <code>TypedArray</code>, or <code>DataView</code> containing the bytes to decode.</li> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>Returns a decoded string, ensuring that any incomplete multibyte characters at the end of the <code>Buffer</code>, or <code>TypedArray</code>, or <code>DataView</code> are omitted from the returned string and stored in an internal buffer for the next call to <code>stringDecoder.write()</code> or <code>stringDecoder.end()</code>.</p> </div> </div> </div> <script src="assets/sh_main.js"></script> <script src="assets/sh_javascript.min.js"></script> <script>highlight(undefined, undefined, 'pre');</script> </body> </html>