urlify.js

// URLify: Write a method to replace all spaces in a string with
// '%20: You may assume that the string has sufficient space at the
// end to hold the additional characters, and that you are given the
// "true" length of the string. (Note: If implementing in Java,
//     please use a character array so that you can perform this operation
//     in place.)

function urlify(input) {
  const formattedUrl = input.trim().replace(/ /g, "%20");
  console.log(formattedUrl);
  return formattedUrl;
}

urlify("he llo ");
urlify("Mr John Smith    ");