Lit vs Polymer: What are the differences?

1. Data Binding: Lit uses a simple syntax for data binding where the templating system automatically updates the UI when the data changes, while Polymer requires additional code for two-way data binding.
2. Performance: Lit offers superior performance due to its lightweight nature and efficient rendering system, whereas Polymer can be heavier and slower due to its full-featured nature, which includes unnecessary features for some applications.
3. Size: Lit has a smaller file size as it includes only the essentials for web components, resulting in quicker load times, whereas Polymer includes a larger set of features which might not be required, making it a bit heavier in comparison.
4. Directives: Lit utilizes standard web platform features like Lit directives, making it more aligned with modern best practices, whereas Polymer has its own set of custom elements and directives, which might require additional learning and maintenance.
5. Composition Patterns: Lit encourages the use of composition patterns for building complex components, leading to better code structure and reusability, while Polymer can sometimes lead to monolithic components that are harder to maintain and reuse.
6. Community Support and Updates: Lit is actively maintained by a team at Google, providing regular updates and support, whereas Polymer has seen a decrease in active development and focus from Google, leading to uncertainties in its long-term support and compatibility.

In Summary, Lit and Polymer differ in their approach to data binding, performance, file size, directives, composition patterns, and community support, with Lit being more streamlined and aligned with modern practices compared to Polymer.