freeCodeCamp/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/missing-letters.chinese.md

id	title	isRequired	challengeType	videoUrl	localeTitle
af7588ade1100bde429baf20	Missing letters	true	5		遗失的信件

Description

在传递的字母范围内找到丢失的字母并将其返回。如果范围内存在所有字母，则返回undefined。如果卡住，请记得使用Read-Search-Ask 。尝试配对程序。编写自己的代码。

Instructions

Tests

tests:
  - text: <code>fearNotLetter(&quot;abce&quot;)</code>应返回“d”。
    testString: 'assert.deepEqual(fearNotLetter("abce"), "d", "<code>fearNotLetter("abce")</code> should return "d".");'
  - text: <code>fearNotLetter(&quot;abcdefghjklmno&quot;)</code>应该返回“i”。
    testString: 'assert.deepEqual(fearNotLetter("abcdefghjklmno"), "i", "<code>fearNotLetter("abcdefghjklmno")</code> should return "i".");'
  - text: <code>fearNotLetter(&quot;stvwx&quot;)</code>应该返回“u”。
    testString: 'assert.deepEqual(fearNotLetter("stvwx"), "u", "<code>fearNotLetter("stvwx")</code> should return "u".");'
  - text: <code>fearNotLetter(&quot;bcdf&quot;)</code>应返回“e”。
    testString: 'assert.deepEqual(fearNotLetter("bcdf"), "e", "<code>fearNotLetter("bcdf")</code> should return "e".");'
  - text: <code>fearNotLetter(&quot;abcdefghijklmnopqrstuvwxyz&quot;)</code>应返回undefined。
    testString: 'assert.isUndefined(fearNotLetter("abcdefghijklmnopqrstuvwxyz"), "<code>fearNotLetter("abcdefghijklmnopqrstuvwxyz")</code> should return undefined.");'

Challenge Seed

function fearNotLetter(str) {
  return str;
}

fearNotLetter("abce");

Solution

// solution required