Modular Code and Dependency Management: The need for better ways to manage dependencies in increasingly complex projects led to the rise of npm for back-end packages and Bower for front-end libraries. It became the backbone for modern JavaScript projects by supporting complex build pipelines and handling assets beyond just JavaScript. This shift required developers to completely rewrite their applications to migrate from AngularJS to Angular (2+), leading many to either switch frameworks or adopt React and Vue, which offered simpler learning curves and better performance.