Modules make dependencies and public exports explicit. Understand the environment's module loading rules rather than assuming a browser and every server runtime behave identically.
Before you begin
Know basic HTML and simple JavaScript expressions. Choose a browser or server runtime deliberately and record how the example is run.
Work through the idea
Make the state, input and expected result explicit before changing the interface. Check the calculation separately from the event handler. Use fictional data and inspect an invalid input as well as a normal one. A visible result should correspond to a completed operation, not merely to a clicked button.
- Export one useful function
- Import it by an explicit path
- Separate reusable logic from startup code
Practice task
Split a small calculator into a calculation module and an interface module.
Check your result
Show which module owns the data and how an import failure is diagnosed.
A mistake to avoid
Do not mix module systems accidentally or hide circular dependencies.
Keep a review note
Save the inputs or scenario, your reasoning and the result you checked. Explain one assumption and one case that needs more work. Revise the exercise after feedback and distinguish what you demonstrated from what remains untested.
Official reference for further study
Explore the related learning path · Choose another worksheet