SonarJS is a static code analyzer for JavaScript, TypeScript, and CSS that integrates with SonarQube to deliver code quality and security analysis. It provides advanced rules based on pattern matching and control flow analysis, supporting 479 JavaScript rules, 496 TypeScript rules, and 29 CSS rules, with compatibility for modern ECMAScript features and frameworks like React JSX and Vue. This tool is designed for developers and teams seeking to improve code quality, maintainability, and security in their JavaScript/TypeScript projects.