JavaScript 模块模式
✏️ Editable
Loading...
Live Preview
⌘+Enter Run⌘+R Reset
About This Exercise
模块模式可以理解成“黑盒子”：
- 盒子里面有私有状态（外部不能直接改）
- 盒子外面只暴露几个方法（next/current/reset）
这样做能减少误操作，也更容易维护。
Intermediate⏱ 20-25 min
Learning Objectives
- 理解“私有状态 + 公开方法”的封装思路
- 掌握工厂函数返回 API 对象的写法
- 学会用闭包保存状态并实现重置能力
Scenario
你在写计数工具：外部只能通过 API 操作计数器，
不能直接改 count 变量，避免多人协作时出现“状态被随意改坏”。
Why Do This
- Frontend JS is not just about knowing the syntax — the key is reliably manipulating the DOM and managing interaction state.
- Break down the event flow (trigger -> handle -> update UI) before coding, and you will make significantly fewer errors.
- Rule-based validation helps you develop a testable frontend mindset.
Hands-on Practice
- Write out the event flow in comments first, then implement the functions.
- Add an edge case branch for invalid input or empty data.
- Explain why each validation rule is needed.
Common Mistakes
- Only testing the happy path without verifying edge inputs or repeated clicks.
- Mixing event binding and state updates together, making future maintenance difficult.
- Console output looks correct but the UI is not actually updated.
Deliverable
A reusable interaction component scaffold (event flow description + key functions + edge case handling).
My Progress
Completed Steps0 / 3
Total Attempts0
Best Score0%
Completion Criteria (Checkable)
Confirm before completing this Lab
Reflection Questions (Recommended)
Describe the event flow of this Lab in 2-3 sentences (trigger -> handle -> update).
What edge case did you add? Why is it easy to miss?
How confident are you with this interaction pattern now?
Tags
JavaScriptModuleClosure