Loose the return statement and make it a oneliner

FP: Don't do a SPACE for a letter match, but a false value, so its easier to test in the 2nd loop function word2colors ( answer = "dread" , guess = "added" ) { answer = answer.split( "" ); return guess .split( "" ) .map( ( letter, idx ) => letter == answer[idx] ? (answer[idx] = false ) : letter ) .map( ( letter, idx ) => letter ? (idx = answer.indexOf(letter)) < 0 ? "GRAY" : (answer[idx] = "YELLOW" ) : "GREEN" ); // ['YELLOW', 'YELLOW', 'GRAY', 'YELLOW', 'GREEN'] } console .log(word2colors()); FYI, why built a clone at all? You can use the Web Components of the original Wordle

FYI, HTML5 has default tags to create an accordion: https://dev.to/dannyengelman/acme-the-accordion-web-component-in-187-bytes-47ah