// filter takes an array and function as argumentfunction
filter(arr, filterFunc) {
const filterArr = []; // empty array
// loop though array
for(let i=0;i<arr.length;i++) {
const result = filterFunc(arr[i], i, arr);
// push the current element if result is true
if(result)
filterArr.push(arr[i]);
}
return filterArr;
}