如果您已经(或正在考虑)使用Lodash,解决方案很容易:

_.upperFirst('fred');
// => 'Fred'

_.upperFirst('FRED');
// => 'FRED'

_.capitalize('fred') //=> 'Fred'

查看他们的文档: https://lodash.com/docs#capitalize

_.camelCase(“Foo Bar”); //=>“FooBar”

https://lodash.com/docs/4.15.0#camelCase

_.lowerFirst('Fred');
// => 'fred'

_.lowerFirst('FRED');
// => 'fRED'

_.snakeCase('Foo Bar');
// => 'foo_bar'

Vanilla JavaScript for first up 案例:

function upperCaseFirst(str){
    return str.charAt(0).toUpperCase() + str.substring(1);
}

函数有两个论点:

起点 - 起点指数; 长度 - 依据的长度为资本化

String.prototype.subUpper = function () {
    var result = this.toString();
    var start = 0;
    var length = 1;
    if (arguments.length > 0) {
        start = arguments[0];
        if (start < this.length) {
            if (arguments.length > 1) {
                length = arguments[1];
            }
            if (start + length > this.length) {
                length = this.length - start;
            }
            var startRest = start + length;
            var prefix = start > 0 ? this.substr(0, start) : String.empty;
            var sub = this.substr(start, length);
            var suffix = this.substr(startRest, this.length - startRest);
            result = prefix + sub.toUpperCase() + suffix;
        }
    }
    return result;
};

这是一个简单的

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

ucfirst函数工作,如果你这样做。

function ucfirst(str) {
    var firstLetter = str.slice(0,1);
    return firstLetter.toUpperCase() + str.substring(1);
}

谢谢JP的解释。

如果您想修改全覆文本,您可能希望修改其他例子如下:

function capitalize (text) {
    return text.charAt(0).toUpperCase() + text.slice(1).toLowerCase();
}

这将确保下列文本进行更改:

TEST => Test
This Is A TeST => This is a test

var capitalizeMe = "string not starting with capital"

资本化与substr

var capitalized = capitalizeMe.substr(0, 1).toUpperCase() + capitalizeMe.substr(1);