JavaScript continues to be a dominant force in web and mobile app development, largely due to its versatility and wide array of frameworks that cater to different development needs. In 2019, React, Vue, and Angular topped the list of front-end frameworks, with React being favored for its efficiency and large community support. Vue gained popularity for its simplicity and ease of integration, while Angular remained a strong choice for its robust features and support for progressive web apps. On the back-end, Express.js led the way as a minimalist and flexible framework for server-side applications, while Next.js emerged as a strong contender with its server-side rendering capabilities. For testing, Jest and Mocha were highlighted for their efficiency and flexibility, with Jest being noted for its speed and ease of use. Each framework offers unique strengths and drawbacks, making the choice of the right framework dependent on the specific requirements of a project.