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May 4, 2026 · View on GitHub

The JavaScript version of Open Chinese Convert (OpenCC)

繁體版 - 简体版

Dictionary data is generated from opencc-data at build time and bundled in the published package. Browser usage does not fetch extra dictionary text files at runtime.

Import

Install opencc-js for Node.js or a bundler

npm install opencc-js

ES modules:

import OpenCC from 'opencc-js';

CommonJS:

const OpenCC = require('opencc-js');

Use opencc-js in a browser

Self-hosted ES module:

<script type="module">
  import OpenCC from './dist/esm/full.js';

  const converter = OpenCC.Converter({ from: 'cn', to: 'tw' });
  console.log(converter('汉语'));
</script>

CDN ES module:

<script type="module">
  import OpenCC from 'https://cdn.jsdelivr.net/npm/opencc-js@1.3.1-next.1/dist/esm/full.js';

  const converter = OpenCC.Converter({ from: 'cn', to: 'tw' });
  console.log(converter('汉语'));
</script>

UMD build for plain script tags:

<script src="https://cdn.jsdelivr.net/npm/opencc-js@1.3.1-next.1/dist/umd/full.js"></script>

Usage

Basic usage

// Convert Traditional Chinese (Hong Kong) to Simplified Chinese (Mainland China)
const converter = OpenCC.Converter({ from: 'hk', to: 'cn' });
console.log(converter('漢語')); // output: 汉语

Custom Converter

const converter = OpenCC.CustomConverter([
  ['香蕉', 'banana'],
  ['蘋果', 'apple'],
  ['梨', 'pear'],
]);
console.log(converter('香蕉 蘋果 梨')); // output: banana apple pear

Or using space and vertical bar as delimiter.

const converter = OpenCC.CustomConverter('香蕉 banana|蘋果 apple|梨 pear');
console.log(converter('香蕉 蘋果 梨')); // output: banana apple pear

Add words

  • Use low-level function ConverterFactory to create converter.
  • Get dictionary from the property Locale.
const customDict = [
  ['“', '「'],
  ['”', '」'],
  ['‘', '『'],
  ['’', '』'],
];
const converter = OpenCC.ConverterFactory(
  OpenCC.Locale.from.cn,                   // Simplified Chinese (Mainland China) => OpenCC standard
  OpenCC.Locale.to.tw.concat([customDict]) // OpenCC standard => Traditional Chinese (Taiwan) with custom words
);
console.log(converter('悟空道：“师父又来了。怎么叫做‘水中捞月’？”'));
// output: 悟空道：「師父又來了。怎麼叫做『水中撈月』？」

This will get the same result with an extra convertion.

const customDict = [
  ['“', '「'],
  ['”', '」'],
  ['‘', '『'],
  ['’', '』'],
];
const converter = OpenCC.ConverterFactory(
  OpenCC.Locale.from.cn, // Simplified Chinese (Mainland China) => OpenCC standard
  OpenCC.Locale.to.tw,   // OpenCC standard => Traditional Chinese (Taiwan)
  [customDict]           // Traditional Chinese (Taiwan) => custom words
);
console.log(converter('悟空道：“师父又来了。怎么叫做‘水中捞月’？”'));
// output: 悟空道：「師父又來了。怎麼叫做『水中撈月』？」

DOM operations

HTML attribute lang='*' defines the targets.

<span lang="zh-HK">漢語</span>

// Set Chinese convert from Traditional (Hong Kong) to Simplified (Mainland China)
const converter = OpenCC.Converter({ from: 'hk', to: 'cn' });
// Set the conversion starting point to the root node, i.e. convert the whole page
const rootNode = document.documentElement;
// Convert all elements with attributes lang='zh-HK'. Change attribute value to lang='zh-CN'
const HTMLConvertHandler = OpenCC.HTMLConverter(converter, rootNode, 'zh-HK', 'zh-CN');
HTMLConvertHandler.convert(); // Convert  -> 汉语
HTMLConvertHandler.restore(); // Restore  -> 漢語

API

  • .Converter({}): declare the converter's direction via locales.
    • default: { from: 'tw', to: 'cn' }
    • syntax : { from: locale1, to: locale2 }
  • locales: letter codes defining a writing locale and, occasionally, its idiomatic habits.
    • cn: Simplified Chinese (Mainland China)
    • tw: Traditional Chinese (Taiwan)
      • twp: with phrase conversion (ex: 自行車 -> 腳踏車）
    • hk: Traditional Chinese (Hong Kong)
    • jp: Japanese Shinjitai
    • t: Traditional Chinese (OpenCC standard. For most use cases, prefer a regional locale such as tw or hk)
  • .CustomConverter([]) : defines custom dictionary.
    • default: []
    • syntax : [ ['item1','replacement1'], ['item2','replacement2'], … ]
  • .HTMLConverter(converter, rootNode, langAttrInitial, langAttrNew ) : uses previously defined converter() to convert all HTML elements text content from a starting root node and down, into the target locale. Also converts all attributes lang from existing langAttrInitial to langAttrNew values, and converts placeholder and aria-label attributes.
  • lang attributes : html attribute defines the languages of the text content to the browser, at start (langAttrInitial) and after conversion (langAttrNew).
  • ignore-opencc : html class signaling an element and its sub-nodes will not be converted.

Bundle optimization

  • Tree Shaking (ES Modules Only) may result less size of bundle file.
  • Using ConverterFactory instead of Converter.
  • Prefer explicit locale dictionaries such as tw, hk, or cn over the generic OpenCC standard t preset.
import * as OpenCC from 'opencc-js/core'; // primary code
import * as Locale from 'opencc-js/preset'; // dictionary

const converter = OpenCC.ConverterFactory(Locale.from.hk, Locale.to.cn);
console.log(converter('漢語'));

Difference from the opencc npm package

The opencc-js npm package is a pure JavaScript implementation for browsers and Node.js. It bundles dictionary data generated from opencc-data, so it does not require native binaries and does not fetch dictionary text files at runtime.

opencc-js has aligned its conversion flow with the official OpenCC implementation, including phrase segmentation for built-in converters, and is tested against upstream OpenCC test cases and golden outputs. It still should not be treated as guaranteed to produce 100% identical results for every possible input.

opencc-js currently supports the built-in OpenCC mmseg-style segmentation used by its bundled converters, but it does not support extended segmentation algorithms such as Jieba.

The opencc npm package is the Node.js native binding for the official OpenCC C++ project. It is intended for Node.js, depends on native or prebuilt binaries, and follows the official OpenCC engine. It can use extended segmentation algorithms such as Jieba when supported by the official OpenCC configuration and runtime.

The opencc-wasm npm package is another browser-capable implementation. It uses WebAssembly, keeps its configuration and conversion logic aligned with the official opencc package, and can support Jieba segmentation through the official OpenCC runtime.