Sentiment Analysis in Node.js Without External APIs

import { sentiment } from 'textlens'; const result = sentiment('I love this product! It works great.'); console.log(result.label); // "positive" console.log(result.comparative); // 0.75 console.log(result.positive); // ["love", "great"] That's sentiment analysis running in Node.js. No API key, no network request, no Python. The entire lexicon ships with the package and runs locally. This article covers how lexicon-based sentiment analysis works, when to use it, and how to build practical features with it: comment moderation, review scoring, and content tone checking. Why sentiment analysis matters Every app that handles user-generated text has an implicit opinion problem. Product reviews, support tickets, blog comments, social media posts—they all carry tone. Knowing that tone unlocks concrete features: Comment moderation — Flag comments with strongly negative sentiment for review before publishing. Review scoring — Aggregate sentiment across product reviews to surface the most positiv