/*

The toUpperCase() method returns the value of the string converted to uppercase.

This method does not affect the value of the string itself since JavaScript strings are immutable.

MDN Link: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase

Characters from A-Z have ASCII code from 65 - 90.

And characters from a-z have ASCII code from 97-122.

We're checking this condition to implement this function.

*/

String.prototype.toUpperCase = function myToUpperCase() {

let upperCaseString = '';

for (let i = 0; i < this.length; i += 1) {

const character = this[i];

const charCode = character.charCodeAt();

if (charCode >= 97 && charCode <= 122) {

upperCaseString += String.fromCharCode(charCode - 32);

} else {

upperCaseString += character;

}

}

return upperCaseString;

};