上面的答案对我来说都不完美，所以我不得不带着自己的自行车:

function camelCaseToTitle(camelCase) {
    if (!camelCase) {
        return '';
    }

    var pascalCase = camelCase.charAt(0).toUpperCase() + camelCase.substr(1);
    return pascalCase
        .replace(/([a-z])([A-Z])/g, '$1 $2')
        .replace(/([A-Z])([A-Z][a-z])/g, '$1 $2')
        .replace(/([a-z])([0-9])/gi, '$1 $2')
        .replace(/([0-9])([a-z])/gi, '$1 $2');
}

测试用例:

null => ''
'' => ''
'simpleString' => 'Simple String'
'stringWithABBREVIATIONInside => 'String With ABBREVIATION Inside'
'stringWithNumber123' => 'String With Number 123'
'complexExampleWith123ABBR890Etc' => 'Complex Example With 123 ABBR 890 Etc'

使用JS的String.prototype.replace()和String.prototype.toUpperCase()

const str = "thisIsATestString"; const res = str.replace (/ ^ [a - z] | [a - z] / g (c i) = >(我吗?": "") + c.toUpperCase()); console.log (res);// "This Is A Test String"

我也遇到过类似的问题，我是这样处理的:

stringValue.replace(/([A-Z]+)*([A-Z][a-z])/g, "$1 $2")

对于更健壮的解决方案:

stringValue.replace(/([A-Z]+)/g, " $1").replace(/([A-Z][a-z])/g, " $1")

http://jsfiddle.net/PeYYQ/

输入:

 helloThere 
 HelloThere 
 ILoveTheUSA
 iLoveTheUSA

输出:

 hello There 
 Hello There 
 I Love The USA
 i Love The USA

没有副作用的例子。

function camel2title(camelCase) {
  // no side-effects
  return camelCase
    // inject space before the upper case letters
    .replace(/([A-Z])/g, function(match) {
       return " " + match;
    })
    // replace first char with upper case
    .replace(/^./, function(match) {
      return match.toUpperCase();
    });
}

在ES6

const camel2title = (camelCase) => camelCase
  .replace(/([A-Z])/g, (match) => ` ${match}`)
  .replace(/^./, (match) => match.toUpperCase())
  .trim();

卧底C程序员。如果你像我一样想保留首字母缩略词，不想看神秘的模式，那么你可能会喜欢这个:

function isUpperCase (str) {
  return str === str.toUpperCase()
}

export function camelCaseToTitle (str) {
  for (let i = str.length - 1; i > 0; i--) {
    if (!isUpperCase(str[i - 1]) && isUpperCase(str[i])) {
      str = str.slice(0, i) + ' ' + str.slice(i)
    }
  }
  return str.charAt(0).toUpperCase() + str.slice(1)
}

const text = 'helloThereMister'; const result = text.replace(/([A-Z])/g， " $1"); const finalResult = result.charAt(0).toUpperCase() + result.slice(1); console.log (finalResult);

第一个字母大写——举个例子。注意“$1”中的空格。

当然，如果第一个字母已经大写了，你就有多余的空间可以删除。