健壮的函数式编程方式做标题大小写函数

Exaplin版本

function toTitleCase(input){
    let output = input
        .split(' ')  // 'HOw aRe YOU' => ['HOw' 'aRe' 'YOU']
        .map((letter) => {
            let firstLetter = letter[0].toUpperCase() // H , a , Y  => H , A , Y
            let restLetters = letter.substring(1).toLowerCase() // Ow, Re, OU => ow, re, ou
            return firstLetter + restLetters // conbine together
        })
        .join(' ') //['How' 'Are' 'You'] => 'How Are You'
    return output
}

实现版本

function toTitleCase(input){
    return input
            .split(' ')
            .map(i => i[0].toUpperCase() + i.substring(1).toLowerCase())
            .join(' ') 
}

toTitleCase('HoW ARe yoU') // reuturn 'How Are You'

我觉得你应该试试这个函数。

var toTitleCase = function (str) {
    str = str.toLowerCase().split(' ');
    for (var i = 0; i < str.length; i++) {
        str[i] = str[i].charAt(0).toUpperCase() + str[i].slice(1);
    }
    return str.join(' ');
};

function titleCase(str) {
    str = str.toLowerCase();

    var strArray = str.split(" ");


    for(var i = 0; i < strArray.length; i++){
        strArray[i] = strArray[i].charAt(0).toUpperCase() + strArray[i].substr(1);

    }

    var result = strArray.join(" ");

    //Return the string
    return result;
}

下面是我的函数，它转换为标题大小写，但也保留了定义的首字母缩写为大写，小词为小写:

String.prototype.toTitleCase = function() {
  var i, j, str, lowers, uppers;
  str = this.replace(/([^\W_]+[^\s-]*) */g, function(txt) {
    return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
  });

  // Certain minor words should be left lowercase unless 
  // they are the first or last words in the string
  lowers = ['A', 'An', 'The', 'And', 'But', 'Or', 'For', 'Nor', 'As', 'At', 
  'By', 'For', 'From', 'In', 'Into', 'Near', 'Of', 'On', 'Onto', 'To', 'With'];
  for (i = 0, j = lowers.length; i < j; i++)
    str = str.replace(new RegExp('\\s' + lowers[i] + '\\s', 'g'), 
      function(txt) {
        return txt.toLowerCase();
      });

  // Certain words such as initialisms or acronyms should be left uppercase
  uppers = ['Id', 'Tv'];
  for (i = 0, j = uppers.length; i < j; i++)
    str = str.replace(new RegExp('\\b' + uppers[i] + '\\b', 'g'), 
      uppers[i].toUpperCase());

  return str;
}

例如:

"TO LOGIN TO THIS SITE and watch tv, please enter a valid id:".toTitleCase();
// Returns: "To Login to This Site and Watch TV, Please Enter a Valid ID:"

ES6内衬

const toTitleCase = string => string.split(' ').map((word) => [word[0].toUpperCase(), ...word.substr(1)].join('')).join(' ');

一种稍微优雅一点的方式，改编了Greg Dean的功能:

String.prototype.toProperCase = function () {
    return this.replace(/\w\S*/g, function(txt){return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();});
};

这样称呼它:

"pascal".toProperCase();