1. Array Summation - Sum all numbers in an array.
const sum = arr => arr.reduce((acc, val) => acc + val, 0);
2. Capitalizing the First Letter of a String
const capitalize = str => str.charAt(0).toUpperCase() + str.slice(1);
3. Checking if a Date is a Weekday
const isWeekday = date => date.getDay() % 6 !== 0;
4. Generating a Random Hex Color
const randomColor = () => `#${Math.floor(Math.random()*0xffffff).toString(16).padEnd(6, '0')}`;
5. Removing Duplicate Values from an Array
const unique = arr => [...new Set(arr)];
6. Toggling a Class in an Element
const toggleClass = (el, className) => el.classList.toggle(className);
7. Checking if a String is a Palindrome
const isPalindrome = str => str === str.split('').reverse().join('');

