Search and replace - algorithm created by LaurelineP - https://repl.it/@LaurelineP/Search-and-replace-algorithm

index.js

function myReplace(str, before, after ) {
  /*
   * 1. Check if the old word has its first letter in a capital or not:
   *    - if yes : return the new word with a capital on the first letter
   *    - if no : return the new word as it is
   */
  let newStr = /^[A-Z]/.test( before[0] )
    ? `${ after.substring( 0, 1 ).toUpperCase()}${ after.substring( 1 ) }`
    : after;

  /*   2. Replace ( oldWord, newWord )  */
  return str.replace( before, newStr );
}

myReplace("Let us get back to more Coding", "Coding", "algorithms")