Practice creating functions!

Define a function maxOrMin that takes three parameters: two numbers and a boolean. Have it return the larger of the two numbers if the boolean is true, otherwise have it return the lesser of the numbers.

Write a function that takes an array of numbers and returns the sum of each number multiplied by its index.

count += (number * index)

Create a function called numSquare that will return an array of all perfect square numbers up to, but not exceeding a max number.

Create a function that returns true if the number passed in is a prime number and false if not.

Using your isPrime function, create a function primes that will return an array of all prime numbers up to, but not exceeding a max number.

Write a function called filter that filters elements of an array based on a callback function.

filter takes in an array and another function (a callback). The callback for filter will take in a number and return true or false (like isPrime does!). Your filter function should create a new array. The filter function should use the callback on each element of the original array. When the callback returns true for an element, filter should add that element to the new array. Make filter return the new array at the end!

// starter structure for our filter function
var filter = function(arr, callback) {
// YOUR CODE IN HERE!

}

// example code to test your function with:
var isOdd = function(num) { 	
  return num % 2 !== 0;
};
filter ([0,1,2,3,4,5], isOdd);
// returns [1, 3, 5]

// you could also try using your isPrime function as the callback:
filter ([8,6,7,5,3,0,9], isPrime);
// returns [7,5,3]