//1. write a function that reverses a string
const strReverser = str => [...str].reverse().join('');

//2. Write a function that filters out numbers from a list
const filterNums = arr => arr.map(Number).filter(e => !isNaN(e));

//3. Write a function that finds an element inside an unsorted list
const findElement = (arr, x) => arr.indexOf(x);

//4. Write a function that showcases the usage of closures
const closureMultiplier = a => b => a * b;

//5. What is a Promise? Write a function that returns a Promise
const promiser = f => new Promise(function(resolve, reject) { resolve(f); });

//6. Write a function that flattens a list of items
const flattener = arr => arr.flat(Infinity);

//7. Write a function that finds an element inside a sorted list
//same as 3

//8. Write a function that accepts two numbers a and b and returns both the division of a and b and their modulo of a and b
const divMod = (a, b) => [a / b, a % b];

//9. Write a function that computes the fibonacci number of N
const fibonacci = n => n <= 2 ? n : fibonacci(n-1) + fibonacci(n-2);

//10. Write a function that accepts a string and returns a map with the strings character frequency
const freqMap = arr => arr.reduce( (acc, val) => { acc.set(val, acc.get(val)+1||1); return acc }, new Map());