Lab briefing · Move state and watch it break

Build a flow that works, MOVE ONE VARIABLE BETWEEN SCOPES THREE TIMES, and RECORD EXACTLY WHAT FAILS AT EACH STEP. Scope is the module's subject and the one thing no explanation makes concrete, because every scope works until the moment it does not. So this lab breaks it on purpose, three times, in a controlled order. BUILD A FLOW OF THREE PAGES WHERE ONE VALUE MATTERS — a selected customer is the clearest. Declare it at FLOW scope, which is the correct answer, and confirm all three pages work. That healthy baseline is what makes each failure legible, exactly as Module 2's lab needed a working request before breaking one. MOVE IT TO PAGE SCOPE FIRST. The page that sets it still works; the other two show nothing. This is the loud failure — immediate, obvious, and in the right place — which is the argument Lesson 3 made for…

In this module: Module 4 · Variables, types and where state lives

1. 1What a variable is here
2. 2The scopes, and what each one meansFree preview
3. 3Choosing a scope, deliberately
4. 4Types, and why you should declare them
5. 5Types that mirror a service
6. 6Computed values and expressions
7. 7Variables that persist
8. 8The event that fires when state changes
9. 9State that four pages need
10. 10Naming state so it is findable
11. 11What breaks: four state failures
12. 12Lab briefing · Move state and watch it break