node-sentiment/index.js

Multilanguage and emojis AFINN-based sentiment analysis for Node.js

"use strict";

/*
 * Multilanguage AFINN-based sentiment analysis for Node.js
 */
let oDictionary = require('./lib/AFINN.js');
let oLangDetect = new (require('languagedetect'));

let textEmoji = require('./lib/textEmojis'); // scores for the text-based emojis

/**
 * Split a sentence into words
 *
 * @param sInput
 * @returns {Array}
 */
function tokenize(sInput) {

    if (sInput.length === 0) {
        return [];
    }

    return sInput
        .toLowerCase()
        .replace(/\r?\n|\r/g, ' ') // line breaks replaced by space https://stackoverflow.com/a/10805292
        .replace(/[.,\/#!$%\^&\*;:{}=_`\"~()]/g, '')
        .replace(/\s{2,}/g, ' ') // remove extra spaces https://stackoverflow.com/a/4328722
        .split(' ');
};

// Performs sentiment analysis on the provided input 'phrase'
module.exports = function (sPhrase, sLangCode, mCallback) {

    if (typeof sPhrase === 'undefined') {
        sPhrase = '';
    }

    // Storage objects
    let aTokens = tokenize(sPhrase),
        iGlobalScore = 0,
        aWords = [],
        aPositive = [],
        aNegative = [],
        bNegation = false;

    // Detect language if needed (beta must be performed on each word for more efficiency)
    if (!sLangCode) {
        let aDetectedLang = oLangDetect.detect(aTokens.join(' '), 1);
        if (aDetectedLang[0]) {
            sLangCode = aDetectedLang[0][0].substring(0, 2);
        }
    }

    // Iterate over tokens
    let len = aTokens.length;
    while (len--) {
        let sToken = String(aTokens[len]), iCurrentScore = 0;

        // Negation flag
        if (oDictionary["negations"][sLangCode] && oDictionary["negations"][sLangCode][sToken]) {
            bNegation = true;
        }

        if (! oDictionary[sLangCode] || ! oDictionary[sLangCode][sToken]) {
            if (! oDictionary['emoji'][sToken]) {
                continue;
            }
            // It's an emoji
            iCurrentScore = Number(oDictionary['emoji'][sToken]);
        } else {
            // It's a word
            iCurrentScore = Number(oDictionary[sLangCode][sToken]);
        }

        aWords.push(String(sToken));
        if (iCurrentScore > 0) {
            aPositive.push(String(sToken));
        } else if (iCurrentScore < 0) {
            aNegative.push(String(sToken));
        }
        iGlobalScore += iCurrentScore;
    }

    // Handle negation detection flag
    iGlobalScore = iGlobalScore * (bNegation === true ? -1 : 1);

    // we execute the function after the negation detection
    getTextEmojis(sPhrase);
    function getTextEmojis(sPhrase) {

        // detect smileys like :) ;) :p :/ =/ :-) :( :D xD :-) ^^
        let regexTextEmojis = new RegExp(/(<[\/\\]?3|[()/|*$][-^]?[:;=]|x[d()]|\^[a-z._-]{?}\^['"]{?}|[:;=B8][\-^]?[3DOPp@$*\\)(\/|])(?=\s|[!.?]|$)/, 'gim');

        let smileyArray;
        while ((smileyArray = regexTextEmojis.exec(sPhrase.toLocaleLowerCase())) !== null) { // convert to lowercase for emojis like :s :S
            const smileyScore = textEmoji['textemoji'][smileyArray[0]]; // get the emoji score
            iGlobalScore += Number(smileyScore); // add the score to the global score

            // add the smiley into the positive/negative arrays
            if (smileyScore > 0) {
                aPositive.push(String(smileyArray[0]));
            } else {
                aNegative.push(String(smileyArray[0]));
            }
        }
    }

    // Handle optional async interface
    let oResult = {
        score: iGlobalScore,
        locale: sLangCode,
        comparative: iGlobalScore / aTokens.length,
        vote: 'neutral',
        tokens: aTokens,
        words: aWords,
        positive: aPositive,
        negative: aNegative,
        negation: bNegation,
        language: sLangCode
    };

    // Classify text as positive, negative or neutral.
    if (oResult.score > 0) {
        oResult.vote = 'positive';
    } else if (oResult.score < 0) {
        oResult.vote = 'negative';
    }

    if (mCallback == null) {
        return oResult;
    }

    process.nextTick(function () {
        mCallback(null, oResult);
    });
};