How do you share code between different Lightning Web Components?

Sharing code between different Lightning Web Components is effectively achieved by creating a utility JavaScript file and importing it into the components that need to use that shared code. This approach promotes code reusability and maintainability.

When you create a utility JavaScript file, you can encapsulate common functions or constants that are needed across multiple components. By using the ES6 import statement, you can import this shared utility into each component that requires it. This not only keeps your code DRY (Don't Repeat Yourself) but also allows you to make changes in one place rather than in multiple components, which can significantly reduce the likelihood of errors and inconsistencies.

The other options would not be effective or advisable. Copying code into each component would lead to duplicated code, making maintenance difficult. Relying on Apex services for code sharing is not appropriate since Apex is primarily used for server-side logic, not for sharing client-side JavaScript code. Referencing code directly in HTML files goes against good practices in modular and maintainable code design, as it could lead to entangled dependencies and harder-to-manage code structures.