你可以使用这样的函数:

function fixStr(str) {
    var out = str.replace(/^\s*/, "");  // strip leading spaces
    out = out.replace(/^[a-z]|[^\s][A-Z]/g, function(str, offset) {
        if (offset == 0) {
            return(str.toUpperCase());
        } else {
            return(str.substr(0,1) + " " + str.substr(1).toUpperCase());
        }
    });
    return(out);
}

"hello World" ==> "Hello World"
"HelloWorld" ==> "Hello World"
"FunInTheSun" ==? "Fun In The Sun"

带有一堆测试字符串的代码:http://jsfiddle.net/jfriend00/FWLuV/。

保留前导空格的替代版本:http://jsfiddle.net/jfriend00/Uy2ac/。

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();

这是我的版本。它在每个小写英文字母后面的大写英文字母之前增加一个空格，如果需要，还会将第一个字母大写:

例如: This IsCamelCase——> This IsCamelCase 这是骆驼案——>这是骆驼案 This IsCamelCase123——>

  function camelCaseToTitleCase(camelCase){
    if (camelCase == null || camelCase == "") {
      return camelCase;
    }

    camelCase = camelCase.trim();
    var newText = "";
    for (var i = 0; i < camelCase.length; i++) {
      if (/[A-Z]/.test(camelCase[i])
          && i != 0
          && /[a-z]/.test(camelCase[i-1])) {
        newText += " ";
      }
      if (i == 0 && /[a-z]/.test(camelCase[i]))
      {
        newText += camelCase[i].toUpperCase();
      } else {
        newText += camelCase[i];
      }
    }

    return newText;
  }

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'

基于上面的一个例子，我想出了这个:

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

它适用于我，因为它使用.trim()来处理边缘情况，其中第一个字母是大写的，并且您最终有一个额外的前导空格。

参考: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim

添加了另一个ES6解决方案，我更喜欢上面的一些想法。

https://codepen.io/902Labs/pen/mxdxRv?editors=0010#0

const camelize = (str) => str
    .split(' ')
    .map(([first, ...theRest]) => (
        `${first.toUpperCase()}${theRest.join('').toLowerCase()}`)
    )
    .join(' ');