leetcode-709-ToLowerCase.js

var toLowerCase = function(str) {
  // let result = [];
  var result = ``;

  str.split('').forEach(char => {
    // find current position
    let current = char.charCodeAt(0);

    if ('A'.charCodeAt(0) <= current) {
      if (current <= 'Z'.charCodeAt(0)) {
        let next = current - 'A'.charCodeAt(0);
        let newCharIndex = 'a'.charCodeAt(0) + next;
        let newChar = String.fromCharCode(newCharIndex);

        result = result + newChar;
      } else {
        result = result + char;
      }
    } else {
      result = result + char;
    }
  });
  return result;
};

module.exports = {
  toLowerCase
}