const factorial = n => n === 0 ? 1 : n * factorial(n - 1);
console.log(factorial(5)); // 輸出 120

const isObject = variable === Object(variable);

const uniqueArray = [...new Set(array)];

const mergedArray = [].concat(...arrays);

const max = Math.max(...array);
const min = Math.min(...array);

const sum = array.reduce((acc, cur) => acc + cur, 0);

const randomInt = Math.floor(Math.random() * (max - min + 1)) + min;

const reversedString = string.split('').reverse().join('');

const isPalindrome = string === string.split('').reverse().join('');

const flattenedArray = array.flat(Infinity);

const randomElement = array[Math.floor(Math.random() * array.length)];

const isUnique = array.length === new Set(array).size;

const compressedString = string.replace(/(.)\1+/g, match => match[0] + match.length);

const fibonacci = Array(n).fill().map((_, i, arr) => i <= 1 ? i : arr[i - 1] + arr[i - 2]);

const intersection = arrays.reduce((acc, cur) => acc.filter(value => cur.includes(value)));

const isValidEmail = /^[\w-]+(\.[\w-]+)*@([\w-]+\.)+[a-zA-Z]{2,7}$/.test(email);

const truthyArray = array.filter(Boolean);

const factorial = n => n <= 1 ? 1 : n * factorial(n - 1);

const isPrime = n => ![...Array(n).keys()].slice(2).some(i => n % i === 0);

const isEmptyObject = Object.keys(object).length === 0 && object.constructor === Object;

const allTrue = array.every(condition);

const anyFalse = array.some(condition);

const sortedArray = array.sort((a, b) => a - b);

const formattedDate = new Date().toISOString().slice(0, 10);

const intValue = +str;

const countOccurrences = array.reduce((acc, cur) => (acc[cur] ? acc[cur]++ : acc[cur] = 1, acc), {});

[a, b] = [b, a];

const result = (expression1, expression2, ..., expressionN);