characterMatch.js

const characterMatch = (stringA, stringB) => {
  // basic optimization - store the lengths
  const aLength = stringA.length;
  const bLength = stringB.length;
  
  // brute force: double for loops
  // loop over the first argument (stringA)
  for (let i = 0; i < aLength; i++) {
    // for every index in stringA, loop over stringB 
    for (let k = 0; k < bLength; k++) {
      // during every loop, every index of stringB is compared
      // to the index of stringA. return true if it's a match
      if (stringA[i] === stringB[k]) {
        return true;    
      }
    }
  }
  // always return false if there's no match
  return false;
};

const HELLO = "Hello";
const GOODBYE = "Goodbye";

characterMatch(HELLO, GOODBYE)