如果你去其中一个 regex 答案,请记住,它们只会与 ASCII 字符一起工作. 所有的 Unicode 字母都不会被打破. XRegExp 图书馆和其 Unicode 插件解决这个问题,如果你想与 regex 保持。

String.prototype.capitalize = function () {
    return this.replace(XRegExp("^\\p{L}"), function ($0) { return $0.toUpperCase(); })
}

考虑到它仍然不涵盖所有可能性(混合字符,见 http://www.regular-expressions.info/unicode.html),似乎更容易使用.charAt(0).toUpperCase() 方法。

var nameP = prompt("please enter your name");
var nameQ = nameP.slice(0,1);
var nameR = nameP.slice(1,100);
nameQ = nameQ.toUpperCase();
nameP = nameQ + nameR;
console.log("Hello! " + nameP);

出口:

Hello! Alex

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

/*
 * As terse as possible, assuming you're using ES version 6+
 */
var upLetter1=s=>s.replace(/./,m=>m.toUpperCase());

console.log(upLetter1("the quick brown fox jumped over the lazy dog."));
//\\ The quick brown fox jumped over the lazy dog. //\\

使用步枪功能:

const capitalize = string => string[0].toUpperCase() + string.slice(1)

优雅

const capitalize = ([firstChar, ...rest]) => `${firstChar.toUpperCase()}${rest.join('')}`;