01_filter_example.js

const vect = [1, 2, 3, 4, 5, 6, 7, 8];

const evenNumbers = vect.filter(number => number % 2 == 0);

console.log(evenNumbers); //[2, 4, 6, 8]

02_copy_if_example.cpp

#include <iostream>
#include <vector>
#include <algorithm>

int main(){
    std::vector<int> vect { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

    std::vector<int> evenNumbers;
    std::copy_if(vect.begin(), vect.end(),  std::back_inserter(evenNumbers),
            [](int number){return number % 2 == 0;});

    for(auto number: evenNumbers)
        std::cout << number << " "; //2 4 6 8
}