48 lines
1.2 KiB
JavaScript
48 lines
1.2 KiB
JavaScript
const learningStatus = "review";
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const records = ["变量", "条件", "函数", null, "对象"];
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let optionalNote;
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const finalComment = null;
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let statusText = "";
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const finishedRecords = [];
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switch (learningStatus) {
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case 'review':
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console.log('已学习')
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break
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case 'ing':
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console.log('学习中');
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break
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case 'prepare':
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console.log('未学习');
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break
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default:
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console.log('状态未知');
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break
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}
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console.log(optionalNote, finalComment);
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for (let i = 0; i < records.length; i++) {
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if (records[i] === null || records[i] === undefined) {
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console.log(`第${i + 1}项为空值，停止读取`)
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break
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} else {
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finishedRecords.push(records[i])
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}
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}
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console.log(finishedRecords)
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// 任务：
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// 1. 用 switch 给 learningStatus 生成说明文字
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// 2. 输出 optionalNote 和 finalComment 分别是什么
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// 3. 用 for 循环读取 records
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// 4. 如果遇到 undefined 或 null，就 break
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// 5. 输出 finishedRecords
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/*用 `switch` 根据学习状态输出不同说明
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- 观察 `undefined` 和 `null` 的区别
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- 用循环读取学习记录
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- 如果读到 `undefined` 或 `null`，立即用 `break` 停止循环
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- 输出停止前已经读取到的内容*/ |