Реализуйте аналог стандартного метода Array#filter.
Это задача на работу с функциями. Поэтому filter будет не методом массива, а функцией,
принимающей
два аргумента, первым из которых является массив.
Аргументы
array — The array filter() was called upon.
callback — A function to execute for each element in the array. It should return a truthy value to keep the element in the resulting array, and a falsy value otherwise. The function is called with the following arguments:
element — The current element being processed in the array.
index — The index of the current element being processed in the array.
array — The array filter() was called upon.
Возвращаемое значение
A shallow copy of the given array containing just the elements that pass the test. If no elements pass the test, an empty array is returned.
Примеры
console.log(filter([1,2,3,4],x=> x >2));// [3, 4]console.log(filter(["a","b","c","d"],(x, i)=> x.length>= i));// ["a", "b"]