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計算 Javascript 中所有字符串字符在字符串中使用字符的次數(shù)

JavaScript

繁星淼淼 2022-06-09 19:04:53

編寫一個名為 strLetterCount 的函數(shù)，它接受一個字符串并返回一個新字符串，每個字符后跟它在字符串中出現(xiàn)的次數(shù)。例如：strLetterCount("taco"); // "t1a1c1o1"我的代碼在這里偏離了標記，但這就是我得到的......我將繼續(xù)尋找每個字母，然后嘗試返回正確的字符串。我知道這不是解決問題的好方法。有什么幫助嗎？function strLetterCount(str) { var countA = 0; var countB = 0; var countC = 0; var countD = 0; var countE = 0; var countF = 0; var countG = 0; var countH = 0; var countI = 0; var countJ = 0; var countK = 0; var countL = 0; var countM = 0; var countN = 0; var countO = 0; var countP = 0; var countQ = 0; var countR = 0; var countS = 0; var countT = 0; var countU = 0; var countV = 0; var countW = 0; var countX = 0; var countY = 0; var countZ = 0; for (var i = 0; i < str.length; i++); if (str[i] === 'a') { countA++; } for (var i = 0; i < str.length; i++); if (str[i] === 'b') { countB++; } for (var i = 0; i < str.length; i++); if (str[i] === 'c') { countC++; } return {"a":countA,"b":countB,"c":countC}}console.log( strLetterCount("The quick brown fox jumps over the lazy dog"))

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3 回答

慕神8447489

TA貢獻1780條經(jīng)驗獲得超1個贊

只需遍歷字符串的每個字符，并將它們計數(shù)到一個對象中。

一個簡單的解決方案是：

let str = "The quick brown fox jumps over the lazy dog";

const count = string => {

const characters = {};

for (let character of string) {

characters[character] = characters[character] + 1 || 1;

}

return characters;

}

console.log(count(str));

您可以將結果用作：

let result = count(str);

console.log(result["o"]); // 4

更新

如果您需要字符串輸出，一種選擇是使用第二個循環(huán)來寫出結果：

let str = "The quick brown fox jumps over the lazy dog";

const count = string => {

const characters = {};

let str = "";

for (let character of string) {

characters[character] = characters[character] + 1 || 1;

}

for (let key in characters) {

str += `${key}${characters[key]}`

}

return str;

}

console.log(count(str));

或者，如果您只是簡單地不關心格式：

return JSON.stringify(characters);

反對回復 2022-06-09

慕尼黑5688855

TA貢獻1848條經(jīng)驗獲得超2個贊

我認為最簡單和最易讀的

const countChars = str => {

const chars = {}; // create a counter object

const arr = str.split(""); // make an array from the characters

arr.forEach(char => chars[char] = ++chars[char] || 1) // add counters to counter object

return arr // return the array but first

.map(char => char + chars[char]) // map to counters

.join(""); // and then join to string

}

console.log(countChars("Now is the time"));

按第一次出現(xiàn)的順序減少到只是 char + number

const countChars = str => {

const chars = {}; // create a counter object

const arr = str.split(""); // make an array from the characters

arr.forEach(char => chars[char] = ++chars[char] || 1) // add counters to counter object

return Object.keys(chars) // return the chars

.map(char => char + chars[char]) // concatenated with counters

.join(""); // and then join to string

}

console.log(countChars("woof the looping loop"));

反對回復 2022-06-09

汪汪一只貓

TA貢獻1898條經(jīng)驗獲得超8個贊

Object.entries()您可以使用,reduce()和flat()方法嘗試此操作：

function strLetterCount(str) {

return Object.entries([...str].reduce(function(ac, s) {

ac[s] = ++ac[s] || 1

return ac;

}, {})).flat().join('')

}

console.log(strLetterCount("taco"))

console.log(strLetterCount("chocotaco"))

解釋：

使用[...str]我們首先將字符串轉換為數(shù)組。
然后使用.reduce()我們試圖將每個字符串元素的計數(shù)和存儲到一個對象中，例如：
```
{t: 1, a: 1, c: 1, o: 1}
```
然后使用Object.entries()我們得到如下數(shù)據(jù)：
```
[["t", 1], ["a", 1], ["c", 1], ["o", 1]]
```
最后使用flat()&join()我們得到所需的輸出格式為字符串t1a1c1o1