JavaScript 实用算法函数

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1) Current Task & Steps

Current task: Step 1 - 第一步：去重并升序
实现 uniqueSorted(nums)，返回 "1,2,3"

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: uniqueSorted(nums)
Self-check: uniqueSorted([3,1,3,2]) => "1,2,3"

2) Beginner Explanation (Current Step)

Step task: 实现 uniqueSorted(nums)，返回 "1,2,3"
Define function(s): uniqueSorted, 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 uniqueSorted(nums) {
  return null;
}
// Self-check: uniqueSorted([3,1,3,2]) should return "1,2,3"
console.log(uniqueSorted([3,1,3,2]));

4) Rule Validation & Hints

📋 当前任务 - Step 1

定义 uniqueSorted
uniqueSorted result

🔐 学习提示

📖 快速参考

排序会修改原数组，若不想影响原数据，请先复制：const copy = [...nums]。

About This Exercise

“算法”不一定是高深题目，很多时候就是把业务需求写成稳定函数。

这关你会完成三类高频工具：

去重 + 排序（清洗数据）
词频统计（分析文本）
TopN 求和（榜单计算）

Intermediate⏱ 20-25 min

Learning Objectives

掌握 Set + sort 的去重排序套路
掌握 Map 频次统计基础写法
掌握 sort + slice + reduce 的 TopN 聚合套路

Scenario

你在做学习数据分析页：需要清洗分数列表、统计关键词数量、计算榜单前 N 名总分。

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