mid exam 03. The Final Quest

 function solve(input) {
                let words = input.shift().split(' ');
                for (let line of input) {
                    if (line === 'Stop') {
                        break;
                    }
                    let tokens = line.split(' ');
                    let command = tokens[0];
                    if (command === 'Delete') {
                        let deleteIndex = Number(tokens[1]);
                        deleteWord(deleteIndex);
                    } else if (command === 'Swap') {
                        let first = tokens[1];
                        let second = tokens[2];
                        swap(first, second);
                    } else if (command === 'Put') {
                        let myword = tokens[1];
                        let index = Number(tokens[2]);
                        put(myword, index);
                    } else if (command === 'Sort') {
                        words.sort(sortByDescending);
                    } else {
                        let first = tokens[1];
                        let second = tokens[2];
                        replace(first, second);
                    }
                }
                console.log(words.join(' '));

                function deleteWord(index) {
                    index = index + 1;
                    if (index >= 0 && index < words.length) {
                        words.splice(index, 1);
                    }
                }

                function swap(word1, word2) {
                    let indexOfFirst = words.indexOf(word1);
                    let indexOfSecond = words.indexOf(word2);

                    if (indexOfFirst !== -1 && indexOfSecond !== -1) {
                        words[indexOfFirst] = word2;
                        words[indexOfSecond] = word1;
                    }
                }

                function put(word, index) {
                    index--;
                    if (index >= 0 && index <= words.length) {
                        words.splice(index, 0, word);
                    }
                }

                function sortByDescending(a, b) {
                    return b.localeCompare(a);
                }

                function replace(word1, word2) {
                    let secondWordIndex = words.indexOf(word2);
                    if (secondWordIndex >= 0 && secondWordIndex < words.length) {
                        words[secondWordIndex] = word1;
                    }
                }
            }