JavaScript ES8 对象工具

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1) Current Task & Steps

Current task: Step 1 - 统计总分：对象值求和
实现 sumValues(obj)，把对象中所有数值字段加总。

Write your code in `script.js` for the current Step.
Click "Run Validation" to check if rules pass.
Once current Step passes, the next step unlocks automatically.
You need to pass Step 1 first to unlock Step 2.

Step Deliverables (Check these)

Define function: sumValues(obj)
Self-check: sumValues({"a":1,"b":2,"c":3}) => 6

2) Beginner Explanation (Current Step)

Step task: 实现 sumValues(obj)，把对象中所有数值字段加总。
Define function(s): sumValues, then verify results with test inputs.
This step has a specific expected result. Focus on making the function return the correct value.
A function is a reusable block of code. Define it first, then call it.
`return` sends a result back. Without return, you usually can't get the function's result.

3) Starter Template (Type along)

function sumValues(obj) {
  return 0;
}
// Self-check: sumValues({"a":1,"b":2,"c":3}) should return 6
console.log(sumValues({"a":1,"b":2,"c":3}));

4) Rule Validation & Hints

📋 当前任务 - Step 1

定义 sumValues
sumValues({a:1,b:2,c:3}) = 6

🔐 学习提示

📖 快速参考

对象先转 entries，处理后再 fromEntries，是前端数据处理高频写法。

About This Exercise

你会经常拿到这样的数据：{a: 1, b: 2, c: 3}。

问题是：对象本身不方便直接做过滤、映射、统计。

ES8 给了你一条很实用的路线：

Object.values：先拿值，做求和统计
Object.entries：拿到 [key, value] 对，做格式化和过滤
Object.fromEntries：把过滤后的键值对再组装回对象

Intermediate⏱ 20-25 min

Learning Objectives

理解 Object.values / entries / fromEntries 的分工
能把对象数据做求和、格式化、筛选
形成“对象 <-> 数组”双向转换思维

Scenario

你在做学习看板的数据处理：需要统计分数、展示键值明细，并把无效项过滤后返回干净对象。

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

All rules for the current step passCan explain each line of your codeCan name a real-world business scenario for this

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?

Not confident yet, need more practiceCan complete similar tasks independentlyCan teach others how to do it