有一些很好的答案，但是，许多人使用正则表达式来查找单词，但是，由于某种原因，没有人使用正则表达式来替换第一个字符。为了解释，我将提供一个较长的解决方案和一个较短的解决方案。

长期解决方案(更具解释性)。通过使用正则表达式[^\s_\-/]*，我们可以找到句子中的每一个单词。随后，我们可以使用正则表达式。与单词中的第一个字符匹配。使用正则表达式版本的replace来替换这两个函数，我们可以像这样更改解决方案:

function toUpperCase(str){返回str.toUpperCase();｝ 函数capitalizeWord(word){返回word.replace(/。/,包含);｝ 函数大写(句子){返回句子。tolowercase()。替换(/ [/ ^ \ s_ \] * / g, capitalizeWord);｝ console.log(大写(“hello world”));//输出:Hello World

对于做同样事情的单个函数，我们将replace调用嵌套如下:

函数大写(句子){ 返回sentence.toLowerCase()。替换(/[^\s_\-/]*/g, function (word) { 返回word.replace(/。/，函数(ch){返回ch. touppercase ();}); }); ｝ console.log(大写(“hello world”));//输出:Hello World

这个解决方案将标点符号考虑到新句子中，处理引用，将小词转换为小写，忽略首字母缩写或全大写单词。

var stopWordsArray = new Array("a", "all", "am", "an", "and", "any", "are", "as", "at", "be", "but", "by", "can", "can't", "did", "didn't", "do", "does", "doesn't", "don't", "else", "for", "get", "gets", "go", "got", "had", "has", "he", "he's", "her", "here", "hers", "hi", "him", "his", "how", "i'd", "i'll", "i'm", "i've", "if", "in", "is", "isn't", "it", "it's", "its", "let", "let's", "may", "me", "my", "no", "of", "off", "on", "our", "ours", "she", "so", "than", "that", "that's", "thats", "the", "their", "theirs", "them", "then", "there", "there's", "these", "they", "they'd", "they'll", "they're", "they've", "this", "those", "to", "too", "try", "until", "us", "want", "wants", "was", "wasn't", "we", "we'd", "we'll", "we're", "we've", "well", "went", "were", "weren't", "what", "what's", "when", "where", "which", "who", "who's", "whose", "why", "will", "with", "won't", "would", "yes", "yet", "you", "you'd", "you'll", "you're", "you've", "your");

// Only significant words are transformed. Handles acronyms and punctuation
String.prototype.toTitleCase = function() {
    var newSentence = true;
    return this.split(/\s+/).map(function(word) {
        if (word == "") { return; }
        var canCapitalise = true;
        // Get the pos of the first alpha char (word might start with " or ')
        var firstAlphaCharPos = word.search(/\w/);
        // Check for uppercase char that is not the first char (might be acronym or all caps)
        if (word.search(/[A-Z]/) > 0) {
            canCapitalise = false;
        } else if (stopWordsArray.indexOf(word) != -1) {
            // Is a stop word and not a new sentence
            word.toLowerCase();
            if (!newSentence) {
                canCapitalise = false;
            }
        }
        // Is this the last word in a sentence?
        newSentence = (word.search(/[\.!\?:]['"]?$/) > 0)? true : false;
        return (canCapitalise)? word.replace(word[firstAlphaCharPos], word[firstAlphaCharPos].toUpperCase()) : word;
    }).join(' ');
}

// Pass a string using dot notation:
alert("A critical examination of Plato's view of the human nature".toTitleCase());
var str = "Ten years on: a study into the effectiveness of NCEA in New Zealand schools";
str.toTitleCase());
str = "\"Where to from here?\" the effectivness of eLearning in childhood education";
alert(str.toTitleCase());

/* Result:
A Critical Examination of Plato's View of the Human Nature.
Ten Years On: A Study Into the Effectiveness of NCEA in New Zealand Schools.
"Where to From Here?" The Effectivness of eLearning in Childhood Education. */

一种方法使用减少

函数titleCase(str) { Const arr = str.split(" "); Const result = arr。Reduce ((acc, cur) => { const newStr = cur[0].toUpperCase() + cur.slice(1).toLowerCase(); 返回${newStr} }, " ") 返回的结果。片(0,result.length-1); ｝

约翰·史密斯->约翰·史密斯

'john smith'.replace(/(^\w|\s+\w){1}/g, function(str){ return str.toUpperCase() } );

这里有一个紧凑的解决方案:

function Title_Case(phrase) 
{
  var revised = phrase.charAt(0).toUpperCase();

  for ( var i = 1; i < phrase.length; i++ ) {

    if (phrase.charAt(i - 1) == " ") {
     revised += phrase.charAt(i).toUpperCase(); }
    else {
     revised += phrase.charAt(i).toLowerCase(); }

   }

return revised;
}

这是我的答案，如果你的问题解决了，请评论并点赞。

function toTitleCase(str) str归来。replace ( / (\ w * w * | w *) \ s * / g, 功能(. txt) { 三年级，四年级，三年级，四年级，三年级，三年级 的 ); 的 < form > 输入: <br /><textarea" > < / textarea > < br / >输出: <br /><textarea" > < / textarea > < / form >