cld/index.js

Language detection for Javascript. Based on the CLD2 (Compact Language Detector) library from Google. Highly optimized for space and speed. Runs about 10x faster than other libraries. Detects over 160 languages. Full test coverage. Runs on Linux, OS X, an

const _    = require('underscore');
const cld2 = require('./build/Release/cld');

module.exports = {
  LANGUAGES          : cld2.LANGUAGES,
  DETECTED_LANGUAGES : cld2.DETECTED_LANGUAGES,
  ENCODINGS          : cld2.ENCODINGS,

  async detect(text, options) {
    let cb = arguments[2];
    if (typeof cb !== 'function' && typeof options === 'function') {
      cb = options;
      options = {};
    }

    try {
      if (arguments.length < 1) {
        throw new Error('Not enough arguments provided');
      }

      if (!_.isString(text) || text.length < 1) {
        throw new Error('Empty or invalid text');
      }

      const defaults = {
        isHTML       : false,
        languageHint : '',
        encodingHint : '',
        tldHint      : '',
        httpHint     : '',
        bestEffort   : false
      };
      options = _.defaults({}, options, defaults);

      if (!_.isBoolean(options.isHTML)) {
        throw new Error('Invalid isHTML value');
      }
      if (!_.isBoolean(options.bestEffort)) {
        throw new Error('Invalid bestEffort value');
      }
      if (!_.isString(options.languageHint)) {
        throw new Error('Invalid languageHint');
      }
      if (!_.isString(options.encodingHint)) {
        throw new Error('Invalid encodingHint');
      }
      if (!_.isString(options.tldHint)) {
        throw new Error('Invalid tldHint');
      }
      if (!_.isString(options.httpHint)) {
        throw new Error('Invalid httpHint');
      }
      if (options.encodingHint.length > 0 &&
        !~cld2.ENCODINGS.indexOf(options.encodingHint)) {

        throw new Error('Invalid encodingHint, see ENCODINGS');
      }
      if (options.languageHint.length > 0 &&
        !~_.keys(cld2.LANGUAGES).indexOf(options.languageHint) &&
        !~_.values(cld2.LANGUAGES).indexOf(options.languageHint)) {

        throw new Error('Invalid languageHint, see LANGUAGES');
      }

      const result = await cld2.detectAsync(
        text,
        !options.isHTML,
        options.languageHint,
        options.encodingHint,
        options.tldHint,
        options.httpHint,
        options.bestEffort
      );

      if (result.languages.length < 1) {
        throw new Error('Failed to identify language');
      }

      if (cb) {
        return cb(null, result);
      } else {
        return result;
      }
    } catch (error) {
      if (cb) {
        cb(error);
      } else {
        throw error;
      }
    }
  }
};