这是个测试——>这是个测试

函数大写(str) { Const word = []; For (let char of str.split(' ')) { word.push(char[0].toUpperCase() + char.slice(1)) ｝ 返回的词。加入(' '); ｝ Console.log(大写("this is a test"));

不使用正则表达式，仅供参考:

String.prototype.toProperCase = function() { Var =这个。分割(' '); Var结果= []; For (var I = 0;I < words.length;我+ +){ var letter = words[i].charAt(0).toUpperCase(); 结果。Push(字母+单词[i].slice(1)); ｝ 返回的结果。加入(' '); }; console.log ( “约翰·史密斯”.toProperCase () ）

一个使用lodash -的解决方案

import { words, lowerCase, capitalize, endsWith, padEnd } from 'lodash';
const titleCase = string =>
  padEnd(
    words(string, /[^ ]+/g)
      .map(lowerCase)
      .map(capitalize)
      .join(' '),
    string.length,
  );

ES-6 way to get title case of a word or entire line.
ex. input = 'hEllo' --> result = 'Hello'
ex. input = 'heLLo woRLd' --> result = 'Hello World'

const getTitleCase = (str) => {
  if(str.toLowerCase().indexOf(' ') > 0) {
    return str.toLowerCase().split(' ').map((word) => {
      return word.replace(word[0], word[0].toUpperCase());
    }).join(' ');
  }
  else {
    return str.slice(0, 1).toUpperCase() + str.slice(1).toLowerCase();
  }
}

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. */

如果可以的话，我强烈建议使用开源的NPM包，这个包在typescript中工作得很好:

NPM: https://www.npmjs.com/package/title-case

Github: https://github.com/blakeembrey/change-case/tree/master/packages/title-case readme

运行npm install title-case将包添加到项目中。

使用标题大小写npm包的示例代码:

import { titleCase } from "title-case";

titleCase("string"); //=> "String"
titleCase("follow step-by-step instructions"); //=> "Follow Step-by-Step Instructions"