change string first letter value javascript code example

Example 1: javascript capitalize first letter

const lower = 'this is an entirely lowercase string';
const upper = lower.charAt(0).toUpperCase() + lower.substring(1);

Example 2: first letter tuUppercase

const string = "tHIS STRING'S CAPITALISATION WILL BE FIXED."
const string = string[0].toUpperCase() + string.slice(1)