下面是2018 ECMAScript 6+ 解决方案:

const str = 'The Eiffel Tower'; const newStr = `${str[0].toUpperCase()}${str.slice(1)}`; console.log('Original String:', str); // the Eiffel Tower console.log('New String:', newStr); // The Eiffel Tower

解決方案 無法閱讀不定義的「charAt」財產

const capitalize = (string) => {
        return string ? string.charAt(0).toUpperCase() + string.slice(1) : "";
    }

console.log(capitalize("i am a programmer")); // I am a programmer

var a = "this is a test"
console.log(a.replace(/^[a-z]/g, txt => txt.toUpperCase()));

let capitalize = (strPara)=>{
    let arr = Array.from(strPara);
    arr[0] = arr[0].toUpperCase();
    return arr.join("");
}

let str = capitalize("this is a test");
console.log(str);

将所有单词的第一字母分为一个字符串:

function ucFirstAllWords( str )
{
    var pieces = str.split(" ");
    for ( var i = 0; i < pieces.length; i++ )
    {
        var j = pieces[i].charAt(0).toUpperCase();
        pieces[i] = j + pieces[i].substr(1);
    }
    return pieces.join(" ");
}

function capitalize(string) {
    return string.replace(/^./, Function.call.bind("".toUpperCase));
}