Capitalizing first letter and replaceAt particular index of String in Javascript

These are the two functions that will help in most cases where we need to replace index of a particular stiring.

Capitalizing first letter of a string can also be done using css property text-transform:capitalize, in many cases such as if we want to show a stirng with first letter capital in title attribute on hover this does'nt work. So this is handy javascript function that will be useful.

//replaceAt index of particluar string

function replaceAt(str, index, replacement) {
    return str.substr(0, index) + replacement + str.substr(index + replacement.length);
}

//capitalize first letter of a string

function capitalizeFirstLetter(string) {

    if(typeof string != "undefined" && string != "" && string != "undefined"){

    return string.charAt(0).toUpperCase() + string.slice(1);

    } else {

            return string;

    }

}