How do I make the first letter of a string uppercase in JavaScript?

Question

How do I make the first letter of a string uppercase, but not change the case of any of the other letters?

For example:

• \"this is a test\"

Answer 1

For another case I need it to capitalize the first letter and lowercase the rest. The following cases made me change this function:

//es5
function capitalize(string) {
    return string.charAt(0).toUpperCase() + string.slice(1).toLowerCase();
}
capitalize("alfredo")  // => "Alfredo"
capitalize("Alejandro")// => "Alejandro
capitalize("ALBERTO")  // => "Alberto"
capitalize("ArMaNdO")  // => "Armando"

// es6 using destructuring 
const capitalize = ([first,...rest]) => first.toUpperCase() + rest.join('').toLowerCase();