Uppercase the first character
importance: 5
Write a function ucFirst(str) that returns the string str with the uppercased first character, for instance:
ucFirst("john") == "John";We can’t “replace” the first character, because strings in JavaScript are immutable.
But we can make a new string based on the existing one, with the uppercased first character:
let newStr = str[0].toUpperCase() + str.slice(1);There’s a small problem though. If str is empty, then str[0] is undefined, and as undefined doesn’t have the toUpperCase() method, we’ll get an error.
The easiest way out is to add a test for an empty string, like this:
function ucFirst(str) {
if (!str) return str;
return str[0].toUpperCase() + str.slice(1);
}
alert( ucFirst("john") ); // John