@somethingthere有一个更紧凑(和现代)的重写方案:

let titleCase = (str => str. tolowercase()。(' ') . map(分裂 c => c. charat (0). touppercase () + c.substring(1))。加入(' ')); 文档。write(titleCase(“我是一个更小的茶壶”));

ECMA2017或ES8

const titleCase = (string) => { return string .split(' ') .map(word => word.substr(0,1).toUpperCase() + word.substr(1,word.length)) .join(' '); }; let result = titleCase('test test test'); console.log(result); Explanation: 1. First, we pass the string "test test test" to our function "titleCase". 2. We split a string on the space basis so the result of first function "split" will be ["test","test","test"] 3. As we got an array, we used map function for manipulation each word in the array. We capitalize the first character and add remaining character to it. 4. In the last, we join the array using space as we split the string by sapce.

这是一个简单的转换方法，可以传递一个值来获得所需的输出。

String.prototype.toChangeCase = function (type) {
    switch (type) {
        case 'upper-first':
            return this.charAt(0).toUpperCase() + this.substr(1).toLowerCase();
        case 'upper-each':
            return this.split(' ').map(word => {
                return word.charAt(0).toUpperCase() + word.substr(1).toLowerCase();
            }).join(' ');
        default:
            throw Error(`In order to get the output pass a value 'upper-first', 'upper-each'`);
    }
}

输出

"capitalize first Letter of Each word in a Sstring".toChangeCase('upper-first')
"Capitalize first letter of each word in a sstring"


"capitalize first Letter of Each word in a Sstring".toChangeCase('upper-each')
"Capitalize First Letter Of Each Word In A Sstring"

"Capitalize First Letter Of Each Word In A String".toChangeCase()
VM380:12 Uncaught Error: In order to get the output pass a value 'upper-first', 'upper-each'
    at String.toChangeCase (<anonymous>:12:19)
    at <anonymous>:16:52

var str = "hello world"
var result = str.split(" ").map(element => {
    return element[0].toUpperCase() + element.slice(1);
});
result = result.join(" ")
console.log(result);

Let cap = (str) => { Let arr = str.split(' '); 加勒比海盗。forEach(函数(项，索引){ Arr [index] = item。替换(项目[0],[0].toUpperCase ()); })； 加勒比海盗。加入(' '); }; console.log(cap(“我是一个小茶壶”));

快速可读版本参见基准http://jsben.ch/k3JVz

请检查下面的代码。

function titleCase(str) {
  var splitStr = str.toLowerCase().split(' ');
  var nstr = ""; 
  for (var i = 0; i < splitStr.length; i++) {
    nstr +=  (splitStr[i].charAt(0).toUpperCase()+ splitStr[i].slice(1) + " 
    ");
  }
  console.log(nstr);
}

var strng = "this is a new demo for checking the string";
titleCase(strng);