fullstack-21-22-learn-programming-with-javascript/more-exercises/solution-exercise-6.js

'use strict'

function makeLowerCase(input) {
  let output = '';
  for (let i = 0; i < input.length; i++) {
    let charCode = input.charCodeAt(i);
    if (charCode >= 65 && charCode <= 95 ) {
        output += String.fromCharCode(charCode + 32);
    } else {
      output += String.fromCharCode(charCode);
    }
  }
  return output;
}

console.log(makeLowerCase('JAVASCRIPT'));