最简单的解决方案是:

let yourSentence = 'it needs first letter upper case';

yourSentence.charAt(0).toUpperCase() + yourSentence.substr(1);

或:

yourSentence.charAt(0).toUpperCase() + yourSentence.slice(1);

或:

yourSentence.substr(0, 1).toUpperCase() + yourSentence.substr(1);

一个可能的解决方案:

function ConvertFirstCharacterToUpperCase(text) {
    return text.substr(0, 1).toUpperCase() + text.substr(1);    
}

使用此:

 alert(ConvertFirstCharacterToUpperCase("this is string"));

此分類上一篇: JS Fiddle

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

这是一个简单的

const upper = lower.replace(/^\w/, c => c.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. //\\

你应该这样做:

let text = "lower case";
text = text.charAt(0).toUpperCase() + text.substring(1, text.length);