这就是同样的行动:

var newStr = string.slice(0,1).toUpperCase() + string.slice(1);

s[0].toUpperCase``+s.substr`1`

let s = 'hello there' console.log( s[0].toUpperCase''+s.substr`1` )

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

该方法将采取一个值,然后将其分成一系列的线条。

const firstLetterToUpperCase = value => {
 return value.replace(
    value.split("")["0"], // Split stirng and get the first letter 
    value
        .split("")
        ["0"].toString()
        .toUpperCase() // Split string and get the first letter to replace it with an uppercase value
  );
};

string = string.replace(string.charAt(0), string.charAt(0).toUpperCase());

第一封信与验证的资本化

function capitalizeFirstLetter(str) {
    return (str && typeof str === 'string') ? (str.charAt(0).toUpperCase() + str.slice(1)) : "";
}

测试

console.log(capitalizeFirstLetter(0)); // Output: ""
console.log(capitalizeFirstLetter(null)); // Output: ""
console.log(capitalizeFirstLetter("test")); // Output: "Test"
console.log(capitalizeFirstLetter({})); // Output: ""