这是一个使用现代javascript实践来提高可读性的完美例子。还没有看到一个减少版本在这里，但这是我使用的。这既是一个咖喱单行和非常可读

sentence
    .trim().toLowerCase()
    .split(' ')
    .reduce((sentence, word) => `${sentence} ${word[0].toUpperCase()}${word.substring(1)}`, '')
    .trim()

Let cap = (str) => { Let arr = str.split(' '); 加勒比海盗。forEach(函数(项，索引){ Arr [index] = item。替换(项目[0],[0].toUpperCase ()); })； 加勒比海盗。加入(' '); }; console.log(cap(“我是一个小茶壶”));

快速可读版本参见基准http://jsben.ch/k3JVz

/* 1. Transform your string into lower case
   2. Split your string into an array. Notice the white space I'm using for the separator
   3. Iterate the new array, and assign the current iteration value (array[c]) a new formatted string:
      - With the sentence: array[c][0].toUpperCase() the first letter of the string converts to upper case.
      - With the sentence: array[c].substring(1) we get the rest of the string (from the second letter index to the last one).
      - The "add" (+) character is for concatenate both strings.
   4. return array.join(' ') // Returns the formatted array like a new string. */


function titleCase(str){
    str = str.toLowerCase();
    var array = str.split(' ');
    for(var c = 0; c < array.length; c++){
        array[c] = array[c][0].toUpperCase() + array[c].substring(1);
    }
    return array.join(' ');
}

titleCase("I'm a little tea pot");

我已经使用下面的代码做到了这一点，希望它能帮助你:

<p id="p1">This is a paragraph.</p>

<script>
   const capitalize = (mySentence) => {
      const words = mySentence.split(" ");
      for (let i = 0; i < words.length; i++) {
         words[i] = words[i][0].toUpperCase() + words[i].substr(1);
      }
      return words.join(" ");
   };  
   const result = capitalize('This is a sample text');
   document.getElementById("p1").innerHTML = result;
</script>

这个例程将处理连字符的单词和带有撇号的单词。

function titleCase(txt) {
    var firstLtr = 0;
    for (var i = 0;i < text.length;i++) {
        if (i == 0 &&/[a-zA-Z]/.test(text.charAt(i)))
            firstLtr = 2;
        if (firstLtr == 0 &&/[a-zA-Z]/.test(text.charAt(i)))
            firstLtr = 2;
        if (firstLtr == 1 &&/[^a-zA-Z]/.test(text.charAt(i))){
            if (text.charAt(i) == "'") {
                if (i + 2 == text.length &&/[a-zA-Z]/.test(text.charAt(i + 1)))
                    firstLtr = 3;
                else if (i + 2 < text.length &&/[^a-zA-Z]/.test(text.charAt(i + 2)))
                    firstLtr = 3;
            }
        if (firstLtr == 3)
            firstLtr = 1;
        else
            firstLtr = 0;
        }
        if (firstLtr == 2) {
            firstLtr = 1;
            text = text.substr(0, i) + text.charAt(i).toUpperCase() + text.substr(i + 1);
        }
        else {
            text = text.substr(0, i) + text.charAt(i).toLowerCase() + text.substr(i + 1);
        }
    }
}

titleCase("pAt o'Neil's");
// returns "Pat O'Neil's";

您没有将更改再次分配给数组，因此您的所有努力都是徒劳的。试试这个:

函数titleCase(str) { var splitStr = str.toLowerCase()。分割(' '); For (var I = 0;i < splitStr.length;我+ +){ //你不需要检查i是否大于splitStr长度，就像你的for为你做的那样 //赋值给数组 splitStr[i] = splitStr[i].charAt(0).toUpperCase() + splitStr[i].substring(1); ｝ //直接返回连接的字符串 splitStr返回。加入(' '); ｝ 文档。write(titleCase(“我是一个小茶壶”));